diff --git a/wp-admin/includes/update-core.php b/wp-admin/includes/update-core.php
index c240fb0ee6..a17c03359a 100644
--- a/wp-admin/includes/update-core.php
+++ b/wp-admin/includes/update-core.php
@@ -865,6 +865,96 @@ $_old_files = array(
 	'wp-includes/blocks/comments-query-loop',
 );
 
+/**
+ * Stores Requests files to be preloaded and deleted.
+ *
+ * For classes/interfaces, use the class/interface name
+ * as the array key.
+ *
+ * All other files/directories should not have a key.
+ *
+ * @since 6.2.0
+ *
+ * @global array $_old_requests_files
+ * @var array
+ * @name $_old_requests_files
+ */
+global $_old_requests_files;
+
+$_old_requests_files = array(
+	// Interfaces.
+	'Requests_Auth'                              => 'wp-includes/Requests/Auth.php',
+	'Requests_Hooker'                            => 'wp-includes/Requests/Hooker.php',
+	'Requests_Proxy'                             => 'wp-includes/Requests/Proxy.php',
+	'Requests_Transport'                         => 'wp-includes/Requests/Transport.php',
+
+	// Classes.
+	'Requests_Auth_Basic'                        => 'wp-includes/Requests/Auth/Basic.php',
+	'Requests_Cookie_Jar'                        => 'wp-includes/Requests/Cookie/Jar.php',
+	'Requests_Exception_HTTP'                    => 'wp-includes/Requests/Exception/HTTP.php',
+	'Requests_Exception_Transport'               => 'wp-includes/Requests/Exception/Transport.php',
+	'Requests_Exception_HTTP_304'                => 'wp-includes/Requests/Exception/HTTP/304.php',
+	'Requests_Exception_HTTP_305'                => 'wp-includes/Requests/Exception/HTTP/305.php',
+	'Requests_Exception_HTTP_306'                => 'wp-includes/Requests/Exception/HTTP/306.php',
+	'Requests_Exception_HTTP_400'                => 'wp-includes/Requests/Exception/HTTP/400.php',
+	'Requests_Exception_HTTP_401'                => 'wp-includes/Requests/Exception/HTTP/401.php',
+	'Requests_Exception_HTTP_402'                => 'wp-includes/Requests/Exception/HTTP/402.php',
+	'Requests_Exception_HTTP_403'                => 'wp-includes/Requests/Exception/HTTP/403.php',
+	'Requests_Exception_HTTP_404'                => 'wp-includes/Requests/Exception/HTTP/404.php',
+	'Requests_Exception_HTTP_405'                => 'wp-includes/Requests/Exception/HTTP/405.php',
+	'Requests_Exception_HTTP_406'                => 'wp-includes/Requests/Exception/HTTP/406.php',
+	'Requests_Exception_HTTP_407'                => 'wp-includes/Requests/Exception/HTTP/407.php',
+	'Requests_Exception_HTTP_408'                => 'wp-includes/Requests/Exception/HTTP/408.php',
+	'Requests_Exception_HTTP_409'                => 'wp-includes/Requests/Exception/HTTP/409.php',
+	'Requests_Exception_HTTP_410'                => 'wp-includes/Requests/Exception/HTTP/410.php',
+	'Requests_Exception_HTTP_411'                => 'wp-includes/Requests/Exception/HTTP/411.php',
+	'Requests_Exception_HTTP_412'                => 'wp-includes/Requests/Exception/HTTP/412.php',
+	'Requests_Exception_HTTP_413'                => 'wp-includes/Requests/Exception/HTTP/413.php',
+	'Requests_Exception_HTTP_414'                => 'wp-includes/Requests/Exception/HTTP/414.php',
+	'Requests_Exception_HTTP_415'                => 'wp-includes/Requests/Exception/HTTP/415.php',
+	'Requests_Exception_HTTP_416'                => 'wp-includes/Requests/Exception/HTTP/416.php',
+	'Requests_Exception_HTTP_417'                => 'wp-includes/Requests/Exception/HTTP/417.php',
+	'Requests_Exception_HTTP_418'                => 'wp-includes/Requests/Exception/HTTP/418.php',
+	'Requests_Exception_HTTP_428'                => 'wp-includes/Requests/Exception/HTTP/428.php',
+	'Requests_Exception_HTTP_429'                => 'wp-includes/Requests/Exception/HTTP/429.php',
+	'Requests_Exception_HTTP_431'                => 'wp-includes/Requests/Exception/HTTP/431.php',
+	'Requests_Exception_HTTP_500'                => 'wp-includes/Requests/Exception/HTTP/500.php',
+	'Requests_Exception_HTTP_501'                => 'wp-includes/Requests/Exception/HTTP/501.php',
+	'Requests_Exception_HTTP_502'                => 'wp-includes/Requests/Exception/HTTP/502.php',
+	'Requests_Exception_HTTP_503'                => 'wp-includes/Requests/Exception/HTTP/503.php',
+	'Requests_Exception_HTTP_504'                => 'wp-includes/Requests/Exception/HTTP/504.php',
+	'Requests_Exception_HTTP_505'                => 'wp-includes/Requests/Exception/HTTP/505.php',
+	'Requests_Exception_HTTP_511'                => 'wp-includes/Requests/Exception/HTTP/511.php',
+	'Requests_Exception_HTTP_Unknown'            => 'wp-includes/Requests/Exception/HTTP/Unknown.php',
+	'Requests_Exception_Transport_cURL'          => 'wp-includes/Requests/Exception/Transport/cURL.php',
+	'Requests_Proxy_HTTP'                        => 'wp-includes/Requests/Proxy/HTTP.php',
+	'Requests_Response_Headers'                  => 'wp-includes/Requests/Response/Headers.php',
+	'Requests_Transport_cURL'                    => 'wp-includes/Requests/Transport/cURL.php',
+	'Requests_Transport_fsockopen'               => 'wp-includes/Requests/Transport/fsockopen.php',
+	'Requests_Utility_CaseInsensitiveDictionary' => 'wp-includes/Requests/Utility/CaseInsensitiveDictionary.php',
+	'Requests_Utility_FilteredIterator'          => 'wp-includes/Requests/Utility/FilteredIterator.php',
+	'Requests_Cookie'                            => 'wp-includes/Requests/Cookie.php',
+	'Requests_Exception'                         => 'wp-includes/Requests/Exception.php',
+	'Requests_Hooks'                             => 'wp-includes/Requests/Hooks.php',
+	'Requests_IDNAEncoder'                       => 'wp-includes/Requests/IDNAEncoder.php',
+	'Requests_IPv6'                              => 'wp-includes/Requests/IPv6.php',
+	'Requests_IRI'                               => 'wp-includes/Requests/IRI.php',
+	'Requests_Response'                          => 'wp-includes/Requests/Response.php',
+	'Requests_SSL'                               => 'wp-includes/Requests/SSL.php',
+	'Requests_Session'                           => 'wp-includes/Requests/Session.php',
+
+	// Directories.
+	'wp-includes/Requests/Auth/',
+	'wp-includes/Requests/Cookie/',
+	'wp-includes/Requests/Exception/HTTP/',
+	'wp-includes/Requests/Exception/Transport/',
+	'wp-includes/Requests/Exception/',
+	'wp-includes/Requests/Proxy/',
+	'wp-includes/Requests/Response/',
+	'wp-includes/Requests/Transport/',
+	'wp-includes/Requests/Utility/',
+);
+
 /**
  * Stores new files in wp-content to copy
  *
@@ -949,6 +1039,7 @@ $_new_bundled_files = array(
  *
  * @global WP_Filesystem_Base $wp_filesystem          WordPress filesystem subclass.
  * @global array              $_old_files
+ * @global array              $_old_requests_files
  * @global array              $_new_bundled_files
  * @global wpdb               $wpdb                   WordPress database abstraction object.
  * @global string             $wp_version
@@ -960,10 +1051,18 @@ $_new_bundled_files = array(
  * @return string|WP_Error New WordPress version on success, WP_Error on failure.
  */
 function update_core( $from, $to ) {
-	global $wp_filesystem, $_old_files, $_new_bundled_files, $wpdb;
+	global $wp_filesystem, $_old_files, $_old_requests_files, $_new_bundled_files, $wpdb;
 
 	set_time_limit( 300 );
 
+	/*
+	 * Merge the old Requests files and directories into the `$_old_files`.
+	 * Then preload these Requests files first, before the files are deleted
+	 * and replaced to ensure the code is in memory if needed.
+	 */
+	$_old_files = array_merge( $_old_files, array_values( $_old_requests_files ) );
+	_preload_old_requests_classes_and_interfaces( $to );
+
 	/**
 	 * Filters feedback messages displayed during the core update process.
 	 *
@@ -1478,6 +1577,48 @@ function update_core( $from, $to ) {
 	return $wp_version;
 }
 
+/**
+ * Preloads old Requests classes and interfaces.
+ *
+ * This function preloads the old Requests code into memory before the
+ * upgrade process deletes the files. Why? Requests code is loaded into
+ * memory via an autoloader, meaning when a class or interface is needed
+ * If a request is in process, Requests could attempt to access code. If
+ * the file is not there, a fatal error could occur. If the file was
+ * replaced, the new code is not compatible with the old, resulting in
+ * a fatal error. Preloading ensures the code is in memory before the
+ * code is updated.
+ *
+ * @since 6.2.0
+ *
+ * @global array              $_old_requests_files Requests files to be preloaded.
+ * @global WP_Filesystem_Base $wp_filesystem       WordPress filesystem subclass.
+ *
+ * @param string $to Path to old WordPress installation.
+ */
+function _preload_old_requests_classes_and_interfaces( $to ) {
+	global $_old_requests_files, $wp_filesystem;
+
+	foreach ( $_old_requests_files as $name => $file ) {
+		// Skip files that aren't interfaces or classes.
+		if ( is_int( $name ) ) {
+			continue;
+		}
+
+		// Skip if it's already loaded.
+		if ( class_exists( $name ) || interface_exists( $name ) ) {
+			continue;
+		}
+
+		// Skip if the file is missing.
+		if ( ! $wp_filesystem->is_file( $to . $file ) ) {
+			continue;
+		}
+
+		require_once $to . $file;
+	}
+}
+
 /**
  * Redirect to the About WordPress page after a successful upgrade.
  *
diff --git a/wp-includes/Requests/Auth.php b/wp-includes/Requests/Auth.php
deleted file mode 100644
index 914c7449ca..0000000000
--- a/wp-includes/Requests/Auth.php
+++ /dev/null
@@ -1,33 +0,0 @@
-<?php
-/**
- * Authentication provider interface
- *
- * @package Requests
- * @subpackage Authentication
- */
-
-/**
- * Authentication provider interface
- *
- * Implement this interface to act as an authentication provider.
- *
- * Parameters should be passed via the constructor where possible, as this
- * makes it much easier for users to use your provider.
- *
- * @see Requests_Hooks
- * @package Requests
- * @subpackage Authentication
- */
-interface Requests_Auth {
-	/**
-	 * Register hooks as needed
-	 *
-	 * This method is called in {@see Requests::request} when the user has set
-	 * an instance as the 'auth' option. Use this callback to register all the
-	 * hooks you'll need.
-	 *
-	 * @see Requests_Hooks::register
-	 * @param Requests_Hooks $hooks Hook system
-	 */
-	public function register(Requests_Hooks $hooks);
-}
diff --git a/wp-includes/Requests/Auth/Basic.php b/wp-includes/Requests/Auth/Basic.php
deleted file mode 100644
index 68d15bd5db..0000000000
--- a/wp-includes/Requests/Auth/Basic.php
+++ /dev/null
@@ -1,88 +0,0 @@
-<?php
-/**
- * Basic Authentication provider
- *
- * @package Requests
- * @subpackage Authentication
- */
-
-/**
- * Basic Authentication provider
- *
- * Provides a handler for Basic HTTP authentication via the Authorization
- * header.
- *
- * @package Requests
- * @subpackage Authentication
- */
-class Requests_Auth_Basic implements Requests_Auth {
-	/**
-	 * Username
-	 *
-	 * @var string
-	 */
-	public $user;
-
-	/**
-	 * Password
-	 *
-	 * @var string
-	 */
-	public $pass;
-
-	/**
-	 * Constructor
-	 *
-	 * @throws Requests_Exception On incorrect number of arguments (`authbasicbadargs`)
-	 * @param array|null $args Array of user and password. Must have exactly two elements
-	 */
-	public function __construct($args = null) {
-		if (is_array($args)) {
-			if (count($args) !== 2) {
-				throw new Requests_Exception('Invalid number of arguments', 'authbasicbadargs');
-			}
-
-			list($this->user, $this->pass) = $args;
-		}
-	}
-
-	/**
-	 * Register the necessary callbacks
-	 *
-	 * @see curl_before_send
-	 * @see fsockopen_header
-	 * @param Requests_Hooks $hooks Hook system
-	 */
-	public function register(Requests_Hooks $hooks) {
-		$hooks->register('curl.before_send', array($this, 'curl_before_send'));
-		$hooks->register('fsockopen.after_headers', array($this, 'fsockopen_header'));
-	}
-
-	/**
-	 * Set cURL parameters before the data is sent
-	 *
-	 * @param resource $handle cURL resource
-	 */
-	public function curl_before_send(&$handle) {
-		curl_setopt($handle, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
-		curl_setopt($handle, CURLOPT_USERPWD, $this->getAuthString());
-	}
-
-	/**
-	 * Add extra headers to the request before sending
-	 *
-	 * @param string $out HTTP header string
-	 */
-	public function fsockopen_header(&$out) {
-		$out .= sprintf("Authorization: Basic %s\r\n", base64_encode($this->getAuthString()));
-	}
-
-	/**
-	 * Get the authentication string (user:pass)
-	 *
-	 * @return string
-	 */
-	public function getAuthString() {
-		return $this->user . ':' . $this->pass;
-	}
-}
diff --git a/wp-includes/Requests/Cookie/Jar.php b/wp-includes/Requests/Cookie/Jar.php
deleted file mode 100644
index a816f90a0a..0000000000
--- a/wp-includes/Requests/Cookie/Jar.php
+++ /dev/null
@@ -1,175 +0,0 @@
-<?php
-/**
- * Cookie holder object
- *
- * @package Requests
- * @subpackage Cookies
- */
-
-/**
- * Cookie holder object
- *
- * @package Requests
- * @subpackage Cookies
- */
-class Requests_Cookie_Jar implements ArrayAccess, IteratorAggregate {
-	/**
-	 * Actual item data
-	 *
-	 * @var array
-	 */
-	protected $cookies = array();
-
-	/**
-	 * Create a new jar
-	 *
-	 * @param array $cookies Existing cookie values
-	 */
-	public function __construct($cookies = array()) {
-		$this->cookies = $cookies;
-	}
-
-	/**
-	 * Normalise cookie data into a Requests_Cookie
-	 *
-	 * @param string|Requests_Cookie $cookie
-	 * @return Requests_Cookie
-	 */
-	public function normalize_cookie($cookie, $key = null) {
-		if ($cookie instanceof Requests_Cookie) {
-			return $cookie;
-		}
-
-		return Requests_Cookie::parse($cookie, $key);
-	}
-
-	/**
-	 * Normalise cookie data into a Requests_Cookie
-	 *
-	 * @codeCoverageIgnore
-	 * @deprecated Use {@see Requests_Cookie_Jar::normalize_cookie}
-	 * @return Requests_Cookie
-	 */
-	public function normalizeCookie($cookie, $key = null) {
-		return $this->normalize_cookie($cookie, $key);
-	}
-
-	/**
-	 * Check if the given item exists
-	 *
-	 * @param string $key Item key
-	 * @return boolean Does the item exist?
-	 */
-	public function offsetExists($key) {
-		return isset($this->cookies[$key]);
-	}
-
-	/**
-	 * Get the value for the item
-	 *
-	 * @param string $key Item key
-	 * @return string|null Item value (null if offsetExists is false)
-	 */
-	public function offsetGet($key) {
-		if (!isset($this->cookies[$key])) {
-			return null;
-		}
-
-		return $this->cookies[$key];
-	}
-
-	/**
-	 * Set the given item
-	 *
-	 * @throws Requests_Exception On attempting to use dictionary as list (`invalidset`)
-	 *
-	 * @param string $key Item name
-	 * @param string $value Item value
-	 */
-	public function offsetSet($key, $value) {
-		if ($key === null) {
-			throw new Requests_Exception('Object is a dictionary, not a list', 'invalidset');
-		}
-
-		$this->cookies[$key] = $value;
-	}
-
-	/**
-	 * Unset the given header
-	 *
-	 * @param string $key
-	 */
-	public function offsetUnset($key) {
-		unset($this->cookies[$key]);
-	}
-
-	/**
-	 * Get an iterator for the data
-	 *
-	 * @return ArrayIterator
-	 */
-	public function getIterator() {
-		return new ArrayIterator($this->cookies);
-	}
-
-	/**
-	 * Register the cookie handler with the request's hooking system
-	 *
-	 * @param Requests_Hooker $hooks Hooking system
-	 */
-	public function register(Requests_Hooker $hooks) {
-		$hooks->register('requests.before_request', array($this, 'before_request'));
-		$hooks->register('requests.before_redirect_check', array($this, 'before_redirect_check'));
-	}
-
-	/**
-	 * Add Cookie header to a request if we have any
-	 *
-	 * As per RFC 6265, cookies are separated by '; '
-	 *
-	 * @param string $url
-	 * @param array $headers
-	 * @param array $data
-	 * @param string $type
-	 * @param array $options
-	 */
-	public function before_request($url, &$headers, &$data, &$type, &$options) {
-		if (!$url instanceof Requests_IRI) {
-			$url = new Requests_IRI($url);
-		}
-
-		if (!empty($this->cookies)) {
-			$cookies = array();
-			foreach ($this->cookies as $key => $cookie) {
-				$cookie = $this->normalize_cookie($cookie, $key);
-
-				// Skip expired cookies
-				if ($cookie->is_expired()) {
-					continue;
-				}
-
-				if ($cookie->domain_matches($url->host)) {
-					$cookies[] = $cookie->format_for_header();
-				}
-			}
-
-			$headers['Cookie'] = implode('; ', $cookies);
-		}
-	}
-
-	/**
-	 * Parse all cookies from a response and attach them to the response
-	 *
-	 * @var Requests_Response $response
-	 */
-	public function before_redirect_check(Requests_Response $return) {
-		$url = $return->url;
-		if (!$url instanceof Requests_IRI) {
-			$url = new Requests_IRI($url);
-		}
-
-		$cookies         = Requests_Cookie::parse_from_headers($return->headers, $url);
-		$this->cookies   = array_merge($this->cookies, $cookies);
-		$return->cookies = $this;
-	}
-}
diff --git a/wp-includes/Requests/Exception/HTTP/429.php b/wp-includes/Requests/Exception/HTTP/429.php
deleted file mode 100644
index 78a3148adf..0000000000
--- a/wp-includes/Requests/Exception/HTTP/429.php
+++ /dev/null
@@ -1,29 +0,0 @@
-<?php
-/**
- * Exception for 429 Too Many Requests responses
- *
- * @see https://tools.ietf.org/html/draft-nottingham-http-new-status-04
- * @package Requests
- */
-
-/**
- * Exception for 429 Too Many Requests responses
- *
- * @see https://tools.ietf.org/html/draft-nottingham-http-new-status-04
- * @package Requests
- */
-class Requests_Exception_HTTP_429 extends Requests_Exception_HTTP {
-	/**
-	 * HTTP status code
-	 *
-	 * @var integer
-	 */
-	protected $code = 429;
-
-	/**
-	 * Reason phrase
-	 *
-	 * @var string
-	 */
-	protected $reason = 'Too Many Requests';
-}
diff --git a/wp-includes/Requests/Exception/Transport.php b/wp-includes/Requests/Exception/Transport.php
deleted file mode 100644
index e60b4884c2..0000000000
--- a/wp-includes/Requests/Exception/Transport.php
+++ /dev/null
@@ -1,5 +0,0 @@
-<?php
-
-class Requests_Exception_Transport extends Requests_Exception {
-
-}
diff --git a/wp-includes/Requests/Hooks.php b/wp-includes/Requests/Hooks.php
deleted file mode 100644
index f857902ced..0000000000
--- a/wp-includes/Requests/Hooks.php
+++ /dev/null
@@ -1,68 +0,0 @@
-<?php
-/**
- * Handles adding and dispatching events
- *
- * @package Requests
- * @subpackage Utilities
- */
-
-/**
- * Handles adding and dispatching events
- *
- * @package Requests
- * @subpackage Utilities
- */
-class Requests_Hooks implements Requests_Hooker {
-	/**
-	 * Registered callbacks for each hook
-	 *
-	 * @var array
-	 */
-	protected $hooks = array();
-
-	/**
-	 * Constructor
-	 */
-	public function __construct() {
-		// pass
-	}
-
-	/**
-	 * Register a callback for a hook
-	 *
-	 * @param string $hook Hook name
-	 * @param callback $callback Function/method to call on event
-	 * @param int $priority Priority number. <0 is executed earlier, >0 is executed later
-	 */
-	public function register($hook, $callback, $priority = 0) {
-		if (!isset($this->hooks[$hook])) {
-			$this->hooks[$hook] = array();
-		}
-		if (!isset($this->hooks[$hook][$priority])) {
-			$this->hooks[$hook][$priority] = array();
-		}
-
-		$this->hooks[$hook][$priority][] = $callback;
-	}
-
-	/**
-	 * Dispatch a message
-	 *
-	 * @param string $hook Hook name
-	 * @param array $parameters Parameters to pass to callbacks
-	 * @return boolean Successfulness
-	 */
-	public function dispatch($hook, $parameters = array()) {
-		if (empty($this->hooks[$hook])) {
-			return false;
-		}
-
-		foreach ($this->hooks[$hook] as $priority => $hooked) {
-			foreach ($hooked as $callback) {
-				call_user_func_array($callback, $parameters);
-			}
-		}
-
-		return true;
-	}
-}
diff --git a/wp-includes/Requests/Proxy.php b/wp-includes/Requests/Proxy.php
deleted file mode 100644
index 0a798dbe9e..0000000000
--- a/wp-includes/Requests/Proxy.php
+++ /dev/null
@@ -1,35 +0,0 @@
-<?php
-/**
- * Proxy connection interface
- *
- * @package Requests
- * @subpackage Proxy
- * @since 1.6
- */
-
-/**
- * Proxy connection interface
- *
- * Implement this interface to handle proxy settings and authentication
- *
- * Parameters should be passed via the constructor where possible, as this
- * makes it much easier for users to use your provider.
- *
- * @see Requests_Hooks
- * @package Requests
- * @subpackage Proxy
- * @since 1.6
- */
-interface Requests_Proxy {
-	/**
-	 * Register hooks as needed
-	 *
-	 * This method is called in {@see Requests::request} when the user has set
-	 * an instance as the 'auth' option. Use this callback to register all the
-	 * hooks you'll need.
-	 *
-	 * @see Requests_Hooks::register
-	 * @param Requests_Hooks $hooks Hook system
-	 */
-	public function register(Requests_Hooks $hooks);
-}
diff --git a/wp-includes/Requests/Response.php b/wp-includes/Requests/Response.php
deleted file mode 100644
index 20861dfb82..0000000000
--- a/wp-includes/Requests/Response.php
+++ /dev/null
@@ -1,122 +0,0 @@
-<?php
-/**
- * HTTP response class
- *
- * Contains a response from Requests::request()
- * @package Requests
- */
-
-/**
- * HTTP response class
- *
- * Contains a response from Requests::request()
- * @package Requests
- */
-class Requests_Response {
-	/**
-	 * Constructor
-	 */
-	public function __construct() {
-		$this->headers = new Requests_Response_Headers();
-		$this->cookies = new Requests_Cookie_Jar();
-	}
-
-	/**
-	 * Response body
-	 *
-	 * @var string
-	 */
-	public $body = '';
-
-	/**
-	 * Raw HTTP data from the transport
-	 *
-	 * @var string
-	 */
-	public $raw = '';
-
-	/**
-	 * Headers, as an associative array
-	 *
-	 * @var Requests_Response_Headers Array-like object representing headers
-	 */
-	public $headers = array();
-
-	/**
-	 * Status code, false if non-blocking
-	 *
-	 * @var integer|boolean
-	 */
-	public $status_code = false;
-
-	/**
-	 * Protocol version, false if non-blocking
-	 *
-	 * @var float|boolean
-	 */
-	public $protocol_version = false;
-
-	/**
-	 * Whether the request succeeded or not
-	 *
-	 * @var boolean
-	 */
-	public $success = false;
-
-	/**
-	 * Number of redirects the request used
-	 *
-	 * @var integer
-	 */
-	public $redirects = 0;
-
-	/**
-	 * URL requested
-	 *
-	 * @var string
-	 */
-	public $url = '';
-
-	/**
-	 * Previous requests (from redirects)
-	 *
-	 * @var array Array of Requests_Response objects
-	 */
-	public $history = array();
-
-	/**
-	 * Cookies from the request
-	 *
-	 * @var Requests_Cookie_Jar Array-like object representing a cookie jar
-	 */
-	public $cookies = array();
-
-	/**
-	 * Is the response a redirect?
-	 *
-	 * @return boolean True if redirect (3xx status), false if not.
-	 */
-	public function is_redirect() {
-		$code = $this->status_code;
-		return in_array($code, array(300, 301, 302, 303, 307), true) || $code > 307 && $code < 400;
-	}
-
-	/**
-	 * Throws an exception if the request was not successful
-	 *
-	 * @throws Requests_Exception If `$allow_redirects` is false, and code is 3xx (`response.no_redirects`)
-	 * @throws Requests_Exception_HTTP On non-successful status code. Exception class corresponds to code (e.g. {@see Requests_Exception_HTTP_404})
-	 * @param boolean $allow_redirects Set to false to throw on a 3xx as well
-	 */
-	public function throw_for_status($allow_redirects = true) {
-		if ($this->is_redirect()) {
-			if (!$allow_redirects) {
-				throw new Requests_Exception('Redirection not allowed', 'response.no_redirects', $this);
-			}
-		}
-		elseif (!$this->success) {
-			$exception = Requests_Exception_HTTP::get_class($this->status_code);
-			throw new $exception(null, $this);
-		}
-	}
-}
diff --git a/wp-includes/Requests/Response/Headers.php b/wp-includes/Requests/Response/Headers.php
deleted file mode 100644
index 12db128ae5..0000000000
--- a/wp-includes/Requests/Response/Headers.php
+++ /dev/null
@@ -1,98 +0,0 @@
-<?php
-/**
- * Case-insensitive dictionary, suitable for HTTP headers
- *
- * @package Requests
- */
-
-/**
- * Case-insensitive dictionary, suitable for HTTP headers
- *
- * @package Requests
- */
-class Requests_Response_Headers extends Requests_Utility_CaseInsensitiveDictionary {
-	/**
-	 * Get the given header
-	 *
-	 * Unlike {@see self::getValues()}, this returns a string. If there are
-	 * multiple values, it concatenates them with a comma as per RFC2616.
-	 *
-	 * Avoid using this where commas may be used unquoted in values, such as
-	 * Set-Cookie headers.
-	 *
-	 * @param string $key
-	 * @return string|null Header value
-	 */
-	public function offsetGet($key) {
-		$key = strtolower($key);
-		if (!isset($this->data[$key])) {
-			return null;
-		}
-
-		return $this->flatten($this->data[$key]);
-	}
-
-	/**
-	 * Set the given item
-	 *
-	 * @throws Requests_Exception On attempting to use dictionary as list (`invalidset`)
-	 *
-	 * @param string $key Item name
-	 * @param string $value Item value
-	 */
-	public function offsetSet($key, $value) {
-		if ($key === null) {
-			throw new Requests_Exception('Object is a dictionary, not a list', 'invalidset');
-		}
-
-		$key = strtolower($key);
-
-		if (!isset($this->data[$key])) {
-			$this->data[$key] = array();
-		}
-
-		$this->data[$key][] = $value;
-	}
-
-	/**
-	 * Get all values for a given header
-	 *
-	 * @param string $key
-	 * @return array|null Header values
-	 */
-	public function getValues($key) {
-		$key = strtolower($key);
-		if (!isset($this->data[$key])) {
-			return null;
-		}
-
-		return $this->data[$key];
-	}
-
-	/**
-	 * Flattens a value into a string
-	 *
-	 * Converts an array into a string by imploding values with a comma, as per
-	 * RFC2616's rules for folding headers.
-	 *
-	 * @param string|array $value Value to flatten
-	 * @return string Flattened value
-	 */
-	public function flatten($value) {
-		if (is_array($value)) {
-			$value = implode(',', $value);
-		}
-
-		return $value;
-	}
-
-	/**
-	 * Get an iterator for the data
-	 *
-	 * Converts the internal
-	 * @return ArrayIterator
-	 */
-	public function getIterator() {
-		return new Requests_Utility_FilteredIterator($this->data, array($this, 'flatten'));
-	}
-}
diff --git a/wp-includes/Requests/Transport.php b/wp-includes/Requests/Transport.php
deleted file mode 100644
index 5146c01d87..0000000000
--- a/wp-includes/Requests/Transport.php
+++ /dev/null
@@ -1,41 +0,0 @@
-<?php
-/**
- * Base HTTP transport
- *
- * @package Requests
- * @subpackage Transport
- */
-
-/**
- * Base HTTP transport
- *
- * @package Requests
- * @subpackage Transport
- */
-interface Requests_Transport {
-	/**
-	 * Perform a request
-	 *
-	 * @param string $url URL to request
-	 * @param array $headers Associative array of request headers
-	 * @param string|array $data Data to send either as the POST body, or as parameters in the URL for a GET/HEAD
-	 * @param array $options Request options, see {@see Requests::response()} for documentation
-	 * @return string Raw HTTP result
-	 */
-	public function request($url, $headers = array(), $data = array(), $options = array());
-
-	/**
-	 * Send multiple requests simultaneously
-	 *
-	 * @param array $requests Request data (array of 'url', 'headers', 'data', 'options') as per {@see Requests_Transport::request}
-	 * @param array $options Global options, see {@see Requests::response()} for documentation
-	 * @return array Array of Requests_Response objects (may contain Requests_Exception or string responses as well)
-	 */
-	public function request_multiple($requests, $options);
-
-	/**
-	 * Self-test whether the transport can be used
-	 * @return bool
-	 */
-	public static function test();
-}
diff --git a/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php b/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php
deleted file mode 100644
index 7eebeb7a72..0000000000
--- a/wp-includes/Requests/Utility/CaseInsensitiveDictionary.php
+++ /dev/null
@@ -1,103 +0,0 @@
-<?php
-/**
- * Case-insensitive dictionary, suitable for HTTP headers
- *
- * @package Requests
- * @subpackage Utilities
- */
-
-/**
- * Case-insensitive dictionary, suitable for HTTP headers
- *
- * @package Requests
- * @subpackage Utilities
- */
-class Requests_Utility_CaseInsensitiveDictionary implements ArrayAccess, IteratorAggregate {
-	/**
-	 * Actual item data
-	 *
-	 * @var array
-	 */
-	protected $data = array();
-
-	/**
-	 * Creates a case insensitive dictionary.
-	 *
-	 * @param array $data Dictionary/map to convert to case-insensitive
-	 */
-	public function __construct(array $data = array()) {
-		foreach ($data as $key => $value) {
-			$this->offsetSet($key, $value);
-		}
-	}
-
-	/**
-	 * Check if the given item exists
-	 *
-	 * @param string $key Item key
-	 * @return boolean Does the item exist?
-	 */
-	public function offsetExists($key) {
-		$key = strtolower($key);
-		return isset($this->data[$key]);
-	}
-
-	/**
-	 * Get the value for the item
-	 *
-	 * @param string $key Item key
-	 * @return string|null Item value (null if offsetExists is false)
-	 */
-	public function offsetGet($key) {
-		$key = strtolower($key);
-		if (!isset($this->data[$key])) {
-			return null;
-		}
-
-		return $this->data[$key];
-	}
-
-	/**
-	 * Set the given item
-	 *
-	 * @throws Requests_Exception On attempting to use dictionary as list (`invalidset`)
-	 *
-	 * @param string $key Item name
-	 * @param string $value Item value
-	 */
-	public function offsetSet($key, $value) {
-		if ($key === null) {
-			throw new Requests_Exception('Object is a dictionary, not a list', 'invalidset');
-		}
-
-		$key              = strtolower($key);
-		$this->data[$key] = $value;
-	}
-
-	/**
-	 * Unset the given header
-	 *
-	 * @param string $key
-	 */
-	public function offsetUnset($key) {
-		unset($this->data[strtolower($key)]);
-	}
-
-	/**
-	 * Get an iterator for the data
-	 *
-	 * @return ArrayIterator
-	 */
-	public function getIterator() {
-		return new ArrayIterator($this->data);
-	}
-
-	/**
-	 * Get the headers as an array
-	 *
-	 * @return array Header data
-	 */
-	public function getAll() {
-		return $this->data;
-	}
-}
diff --git a/wp-includes/Requests/Utility/FilteredIterator.php b/wp-includes/Requests/Utility/FilteredIterator.php
deleted file mode 100644
index 7c6c2c0238..0000000000
--- a/wp-includes/Requests/Utility/FilteredIterator.php
+++ /dev/null
@@ -1,65 +0,0 @@
-<?php
-/**
- * Iterator for arrays requiring filtered values
- *
- * @package Requests
- * @subpackage Utilities
- */
-
-/**
- * Iterator for arrays requiring filtered values
- *
- * @package Requests
- * @subpackage Utilities
- */
-class Requests_Utility_FilteredIterator extends ArrayIterator {
-	/**
-	 * Callback to run as a filter
-	 *
-	 * @var callable
-	 */
-	protected $callback;
-
-	/**
-	 * Create a new iterator
-	 *
-	 * @param array $data
-	 * @param callable $callback Callback to be called on each value
-	 */
-	public function __construct($data, $callback) {
-		parent::__construct($data);
-
-		$this->callback = $callback;
-	}
-
-	/**
-	 * Get the current item's value after filtering
-	 *
-	 * @return string
-	 */
-	public function current() {
-		$value = parent::current();
-
-		if (is_callable($this->callback)) {
-			$value = call_user_func($this->callback, $value);
-		}
-
-		return $value;
-	}
-
-	/**
-	 * @inheritdoc
-	 */
-	public function unserialize($serialized) {}
-
-	/**
-	 * @inheritdoc
-	 *
-	 * @phpcs:disable PHPCompatibility.FunctionNameRestrictions.ReservedFunctionNames.MethodDoubleUnderscore,PHPCompatibility.FunctionNameRestrictions.NewMagicMethods.__unserializeFound
-	 */
-	public function __unserialize($serialized) {}
-
-	public function __wakeup() {
-		unset($this->callback);
-	}
-}
diff --git a/wp-includes/Requests/src/Auth.php b/wp-includes/Requests/src/Auth.php
new file mode 100644
index 0000000000..63ebb08333
--- /dev/null
+++ b/wp-includes/Requests/src/Auth.php
@@ -0,0 +1,36 @@
+<?php
+/**
+ * Authentication provider interface
+ *
+ * @package Requests\Authentication
+ */
+
+namespace WpOrg\Requests;
+
+use WpOrg\Requests\Hooks;
+
+/**
+ * Authentication provider interface
+ *
+ * Implement this interface to act as an authentication provider.
+ *
+ * Parameters should be passed via the constructor where possible, as this
+ * makes it much easier for users to use your provider.
+ *
+ * @see \WpOrg\Requests\Hooks
+ *
+ * @package Requests\Authentication
+ */
+interface Auth {
+	/**
+	 * Register hooks as needed
+	 *
+	 * This method is called in {@see \WpOrg\Requests\Requests::request()} when the user
+	 * has set an instance as the 'auth' option. Use this callback to register all the
+	 * hooks you'll need.
+	 *
+	 * @see \WpOrg\Requests\Hooks::register()
+	 * @param \WpOrg\Requests\Hooks $hooks Hook system
+	 */
+	public function register(Hooks $hooks);
+}
diff --git a/wp-includes/Requests/src/Auth/Basic.php b/wp-includes/Requests/src/Auth/Basic.php
new file mode 100644
index 0000000000..8ea0eb5538
--- /dev/null
+++ b/wp-includes/Requests/src/Auth/Basic.php
@@ -0,0 +1,103 @@
+<?php
+/**
+ * Basic Authentication provider
+ *
+ * @package Requests\Authentication
+ */
+
+namespace WpOrg\Requests\Auth;
+
+use WpOrg\Requests\Auth;
+use WpOrg\Requests\Exception\ArgumentCount;
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Hooks;
+
+/**
+ * Basic Authentication provider
+ *
+ * Provides a handler for Basic HTTP authentication via the Authorization
+ * header.
+ *
+ * @package Requests\Authentication
+ */
+class Basic implements Auth {
+	/**
+	 * Username
+	 *
+	 * @var string
+	 */
+	public $user;
+
+	/**
+	 * Password
+	 *
+	 * @var string
+	 */
+	public $pass;
+
+	/**
+	 * Constructor
+	 *
+	 * @since 2.0 Throws an `InvalidArgument` exception.
+	 * @since 2.0 Throws an `ArgumentCount` exception instead of the Requests base `Exception.
+	 *
+	 * @param array|null $args Array of user and password. Must have exactly two elements
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not an array or null.
+	 * @throws \WpOrg\Requests\Exception\ArgumentCount   On incorrect number of array elements (`authbasicbadargs`).
+	 */
+	public function __construct($args = null) {
+		if (is_array($args)) {
+			if (count($args) !== 2) {
+				throw ArgumentCount::create('an array with exactly two elements', count($args), 'authbasicbadargs');
+			}
+
+			list($this->user, $this->pass) = $args;
+			return;
+		}
+
+		if ($args !== null) {
+			throw InvalidArgument::create(1, '$args', 'array|null', gettype($args));
+		}
+	}
+
+	/**
+	 * Register the necessary callbacks
+	 *
+	 * @see \WpOrg\Requests\Auth\Basic::curl_before_send()
+	 * @see \WpOrg\Requests\Auth\Basic::fsockopen_header()
+	 * @param \WpOrg\Requests\Hooks $hooks Hook system
+	 */
+	public function register(Hooks $hooks) {
+		$hooks->register('curl.before_send', [$this, 'curl_before_send']);
+		$hooks->register('fsockopen.after_headers', [$this, 'fsockopen_header']);
+	}
+
+	/**
+	 * Set cURL parameters before the data is sent
+	 *
+	 * @param resource|\CurlHandle $handle cURL handle
+	 */
+	public function curl_before_send(&$handle) {
+		curl_setopt($handle, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
+		curl_setopt($handle, CURLOPT_USERPWD, $this->getAuthString());
+	}
+
+	/**
+	 * Add extra headers to the request before sending
+	 *
+	 * @param string $out HTTP header string
+	 */
+	public function fsockopen_header(&$out) {
+		$out .= sprintf("Authorization: Basic %s\r\n", base64_encode($this->getAuthString()));
+	}
+
+	/**
+	 * Get the authentication string (user:pass)
+	 *
+	 * @return string
+	 */
+	public function getAuthString() {
+		return $this->user . ':' . $this->pass;
+	}
+}
diff --git a/wp-includes/Requests/src/Autoload.php b/wp-includes/Requests/src/Autoload.php
new file mode 100644
index 0000000000..26dd280ee8
--- /dev/null
+++ b/wp-includes/Requests/src/Autoload.php
@@ -0,0 +1,187 @@
+<?php
+/**
+ * Autoloader for Requests for PHP.
+ *
+ * Include this file if you'd like to avoid having to create your own autoloader.
+ *
+ * @package Requests
+ * @since   2.0.0
+ *
+ * @codeCoverageIgnore
+ */
+
+namespace WpOrg\Requests;
+
+/*
+ * Ensure the autoloader is only declared once.
+ * This safeguard is in place as this is the typical entry point for this library
+ * and this file being required unconditionally could easily cause
+ * fatal "Class already declared" errors.
+ */
+if (class_exists('WpOrg\Requests\Autoload') === false) {
+
+	/**
+	 * Autoloader for Requests for PHP.
+	 *
+	 * This autoloader supports the PSR-4 based Requests 2.0.0 classes in a case-sensitive manner
+	 * as the most common server OS-es are case-sensitive and the file names are in mixed case.
+	 *
+	 * For the PSR-0 Requests 1.x BC-layer, requested classes will be treated case-insensitively.
+	 *
+	 * @package Requests
+	 */
+	final class Autoload {
+
+		/**
+		 * List of the old PSR-0 class names in lowercase as keys with their PSR-4 case-sensitive name as a value.
+		 *
+		 * @var array
+		 */
+		private static $deprecated_classes = [
+			// Interfaces.
+			'requests_auth'                              => '\WpOrg\Requests\Auth',
+			'requests_hooker'                            => '\WpOrg\Requests\HookManager',
+			'requests_proxy'                             => '\WpOrg\Requests\Proxy',
+			'requests_transport'                         => '\WpOrg\Requests\Transport',
+
+			// Classes.
+			'requests_cookie'                            => '\WpOrg\Requests\Cookie',
+			'requests_exception'                         => '\WpOrg\Requests\Exception',
+			'requests_hooks'                             => '\WpOrg\Requests\Hooks',
+			'requests_idnaencoder'                       => '\WpOrg\Requests\IdnaEncoder',
+			'requests_ipv6'                              => '\WpOrg\Requests\Ipv6',
+			'requests_iri'                               => '\WpOrg\Requests\Iri',
+			'requests_response'                          => '\WpOrg\Requests\Response',
+			'requests_session'                           => '\WpOrg\Requests\Session',
+			'requests_ssl'                               => '\WpOrg\Requests\Ssl',
+			'requests_auth_basic'                        => '\WpOrg\Requests\Auth\Basic',
+			'requests_cookie_jar'                        => '\WpOrg\Requests\Cookie\Jar',
+			'requests_proxy_http'                        => '\WpOrg\Requests\Proxy\Http',
+			'requests_response_headers'                  => '\WpOrg\Requests\Response\Headers',
+			'requests_transport_curl'                    => '\WpOrg\Requests\Transport\Curl',
+			'requests_transport_fsockopen'               => '\WpOrg\Requests\Transport\Fsockopen',
+			'requests_utility_caseinsensitivedictionary' => '\WpOrg\Requests\Utility\CaseInsensitiveDictionary',
+			'requests_utility_filterediterator'          => '\WpOrg\Requests\Utility\FilteredIterator',
+			'requests_exception_http'                    => '\WpOrg\Requests\Exception\Http',
+			'requests_exception_transport'               => '\WpOrg\Requests\Exception\Transport',
+			'requests_exception_transport_curl'          => '\WpOrg\Requests\Exception\Transport\Curl',
+			'requests_exception_http_304'                => '\WpOrg\Requests\Exception\Http\Status304',
+			'requests_exception_http_305'                => '\WpOrg\Requests\Exception\Http\Status305',
+			'requests_exception_http_306'                => '\WpOrg\Requests\Exception\Http\Status306',
+			'requests_exception_http_400'                => '\WpOrg\Requests\Exception\Http\Status400',
+			'requests_exception_http_401'                => '\WpOrg\Requests\Exception\Http\Status401',
+			'requests_exception_http_402'                => '\WpOrg\Requests\Exception\Http\Status402',
+			'requests_exception_http_403'                => '\WpOrg\Requests\Exception\Http\Status403',
+			'requests_exception_http_404'                => '\WpOrg\Requests\Exception\Http\Status404',
+			'requests_exception_http_405'                => '\WpOrg\Requests\Exception\Http\Status405',
+			'requests_exception_http_406'                => '\WpOrg\Requests\Exception\Http\Status406',
+			'requests_exception_http_407'                => '\WpOrg\Requests\Exception\Http\Status407',
+			'requests_exception_http_408'                => '\WpOrg\Requests\Exception\Http\Status408',
+			'requests_exception_http_409'                => '\WpOrg\Requests\Exception\Http\Status409',
+			'requests_exception_http_410'                => '\WpOrg\Requests\Exception\Http\Status410',
+			'requests_exception_http_411'                => '\WpOrg\Requests\Exception\Http\Status411',
+			'requests_exception_http_412'                => '\WpOrg\Requests\Exception\Http\Status412',
+			'requests_exception_http_413'                => '\WpOrg\Requests\Exception\Http\Status413',
+			'requests_exception_http_414'                => '\WpOrg\Requests\Exception\Http\Status414',
+			'requests_exception_http_415'                => '\WpOrg\Requests\Exception\Http\Status415',
+			'requests_exception_http_416'                => '\WpOrg\Requests\Exception\Http\Status416',
+			'requests_exception_http_417'                => '\WpOrg\Requests\Exception\Http\Status417',
+			'requests_exception_http_418'                => '\WpOrg\Requests\Exception\Http\Status418',
+			'requests_exception_http_428'                => '\WpOrg\Requests\Exception\Http\Status428',
+			'requests_exception_http_429'                => '\WpOrg\Requests\Exception\Http\Status429',
+			'requests_exception_http_431'                => '\WpOrg\Requests\Exception\Http\Status431',
+			'requests_exception_http_500'                => '\WpOrg\Requests\Exception\Http\Status500',
+			'requests_exception_http_501'                => '\WpOrg\Requests\Exception\Http\Status501',
+			'requests_exception_http_502'                => '\WpOrg\Requests\Exception\Http\Status502',
+			'requests_exception_http_503'                => '\WpOrg\Requests\Exception\Http\Status503',
+			'requests_exception_http_504'                => '\WpOrg\Requests\Exception\Http\Status504',
+			'requests_exception_http_505'                => '\WpOrg\Requests\Exception\Http\Status505',
+			'requests_exception_http_511'                => '\WpOrg\Requests\Exception\Http\Status511',
+			'requests_exception_http_unknown'            => '\WpOrg\Requests\Exception\Http\StatusUnknown',
+		];
+
+		/**
+		 * Register the autoloader.
+		 *
+		 * Note: the autoloader is *prepended* in the autoload queue.
+		 * This is done to ensure that the Requests 2.0 autoloader takes precedence
+		 * over a potentially (dependency-registered) Requests 1.x autoloader.
+		 *
+		 * @internal This method contains a safeguard against the autoloader being
+		 * registered multiple times. This safeguard uses a global constant to
+		 * (hopefully/in most cases) still function correctly, even if the
+		 * class would be renamed.
+		 *
+		 * @return void
+		 */
+		public static function register() {
+			if (defined('REQUESTS_AUTOLOAD_REGISTERED') === false) {
+				spl_autoload_register([self::class, 'load'], true);
+				define('REQUESTS_AUTOLOAD_REGISTERED', true);
+			}
+		}
+
+		/**
+		 * Autoloader.
+		 *
+		 * @param string $class_name Name of the class name to load.
+		 *
+		 * @return bool Whether a class was loaded or not.
+		 */
+		public static function load($class_name) {
+			// Check that the class starts with "Requests" (PSR-0) or "WpOrg\Requests" (PSR-4).
+			$psr_4_prefix_pos = strpos($class_name, 'WpOrg\\Requests\\');
+
+			if (stripos($class_name, 'Requests') !== 0 && $psr_4_prefix_pos !== 0) {
+				return false;
+			}
+
+			$class_lower = strtolower($class_name);
+
+			if ($class_lower === 'requests') {
+				// Reference to the original PSR-0 Requests class.
+				$file = dirname(__DIR__) . '/library/Requests.php';
+			} elseif ($psr_4_prefix_pos === 0) {
+				// PSR-4 classname.
+				$file = __DIR__ . '/' . strtr(substr($class_name, 15), '\\', '/') . '.php';
+			}
+
+			if (isset($file) && file_exists($file)) {
+				include $file;
+				return true;
+			}
+
+			/*
+			 * Okay, so the class starts with "Requests", but we couldn't find the file.
+			 * If this is one of the deprecated/renamed PSR-0 classes being requested,
+			 * let's alias it to the new name and throw a deprecation notice.
+			 */
+			if (isset(self::$deprecated_classes[$class_lower])) {
+				/*
+				 * Integrators who cannot yet upgrade to the PSR-4 class names can silence deprecations
+				 * by defining a `REQUESTS_SILENCE_PSR0_DEPRECATIONS` constant and setting it to `true`.
+				 * The constant needs to be defined before the first deprecated class is requested
+				 * via this autoloader.
+				 */
+				if (!defined('REQUESTS_SILENCE_PSR0_DEPRECATIONS') || REQUESTS_SILENCE_PSR0_DEPRECATIONS !== true) {
+					// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_trigger_error
+					trigger_error(
+						'The PSR-0 `Requests_...` class names in the Request library are deprecated.'
+						. ' Switch to the PSR-4 `WpOrg\Requests\...` class names at your earliest convenience.',
+						E_USER_DEPRECATED
+					);
+
+					// Prevent the deprecation notice from being thrown twice.
+					if (!defined('REQUESTS_SILENCE_PSR0_DEPRECATIONS')) {
+						define('REQUESTS_SILENCE_PSR0_DEPRECATIONS', true);
+					}
+				}
+
+				// Create an alias and let the autoloader recursively kick in to load the PSR-4 class.
+				return class_alias(self::$deprecated_classes[$class_lower], $class_name, true);
+			}
+
+			return false;
+		}
+	}
+}
diff --git a/wp-includes/Requests/src/Capability.php b/wp-includes/Requests/src/Capability.php
new file mode 100644
index 0000000000..87b8340a34
--- /dev/null
+++ b/wp-includes/Requests/src/Capability.php
@@ -0,0 +1,36 @@
+<?php
+/**
+ * Capability interface declaring the known capabilities.
+ *
+ * @package Requests\Utilities
+ */
+
+namespace WpOrg\Requests;
+
+/**
+ * Capability interface declaring the known capabilities.
+ *
+ * This is used as the authoritative source for which capabilities can be queried.
+ *
+ * @package Requests\Utilities
+ */
+interface Capability {
+
+	/**
+	 * Support for SSL.
+	 *
+	 * @var string
+	 */
+	const SSL = 'ssl';
+
+	/**
+	 * Collection of all capabilities supported in Requests.
+	 *
+	 * Note: this does not automatically mean that the capability will be supported for your chosen transport!
+	 *
+	 * @var array<string>
+	 */
+	const ALL = [
+		self::SSL,
+	];
+}
diff --git a/wp-includes/Requests/Cookie.php b/wp-includes/Requests/src/Cookie.php
similarity index 68%
rename from wp-includes/Requests/Cookie.php
rename to wp-includes/Requests/src/Cookie.php
index 7dd5b6822d..ccbbc73dbc 100644
--- a/wp-includes/Requests/Cookie.php
+++ b/wp-includes/Requests/src/Cookie.php
@@ -2,17 +2,23 @@
 /**
  * Cookie storage object
  *
- * @package Requests
- * @subpackage Cookies
+ * @package Requests\Cookies
  */
 
+namespace WpOrg\Requests;
+
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Iri;
+use WpOrg\Requests\Response\Headers;
+use WpOrg\Requests\Utility\CaseInsensitiveDictionary;
+use WpOrg\Requests\Utility\InputValidator;
+
 /**
  * Cookie storage object
  *
- * @package Requests
- * @subpackage Cookies
+ * @package Requests\Cookies
  */
-class Requests_Cookie {
+class Cookie {
 	/**
 	 * Cookie name.
 	 *
@@ -33,9 +39,9 @@ class Requests_Cookie {
 	 * Valid keys are (currently) path, domain, expires, max-age, secure and
 	 * httponly.
 	 *
-	 * @var Requests_Utility_CaseInsensitiveDictionary|array Array-like object
+	 * @var \WpOrg\Requests\Utility\CaseInsensitiveDictionary|array Array-like object
 	 */
-	public $attributes = array();
+	public $attributes = [];
 
 	/**
 	 * Cookie flags
@@ -45,7 +51,7 @@ class Requests_Cookie {
 	 *
 	 * @var array
 	 */
-	public $flags = array();
+	public $flags = [];
 
 	/**
 	 * Reference time for relative calculations
@@ -62,18 +68,46 @@ class Requests_Cookie {
 	 *
 	 * @param string $name
 	 * @param string $value
-	 * @param array|Requests_Utility_CaseInsensitiveDictionary $attributes Associative array of attribute data
+	 * @param array|\WpOrg\Requests\Utility\CaseInsensitiveDictionary $attributes Associative array of attribute data
+	 * @param array $flags
+	 * @param int|null $reference_time
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $name argument is not a string.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $value argument is not a string.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $attributes argument is not an array or iterable object with array access.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $flags argument is not an array.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $reference_time argument is not an integer or null.
 	 */
-	public function __construct($name, $value, $attributes = array(), $flags = array(), $reference_time = null) {
+	public function __construct($name, $value, $attributes = [], $flags = [], $reference_time = null) {
+		if (is_string($name) === false) {
+			throw InvalidArgument::create(1, '$name', 'string', gettype($name));
+		}
+
+		if (is_string($value) === false) {
+			throw InvalidArgument::create(2, '$value', 'string', gettype($value));
+		}
+
+		if (InputValidator::has_array_access($attributes) === false || InputValidator::is_iterable($attributes) === false) {
+			throw InvalidArgument::create(3, '$attributes', 'array|ArrayAccess&Traversable', gettype($attributes));
+		}
+
+		if (is_array($flags) === false) {
+			throw InvalidArgument::create(4, '$flags', 'array', gettype($flags));
+		}
+
+		if ($reference_time !== null && is_int($reference_time) === false) {
+			throw InvalidArgument::create(5, '$reference_time', 'integer|null', gettype($reference_time));
+		}
+
 		$this->name       = $name;
 		$this->value      = $value;
 		$this->attributes = $attributes;
-		$default_flags    = array(
+		$default_flags    = [
 			'creation'    => time(),
 			'last-access' => time(),
 			'persistent'  => false,
 			'host-only'   => true,
-		);
+		];
 		$this->flags      = array_merge($default_flags, $flags);
 
 		$this->reference_time = time();
@@ -84,6 +118,15 @@ class Requests_Cookie {
 		$this->normalize();
 	}
 
+	/**
+	 * Get the cookie value
+	 *
+	 * Attributes and other data can be accessed via methods.
+	 */
+	public function __toString() {
+		return $this->value;
+	}
+
 	/**
 	 * Check if a cookie is expired.
 	 *
@@ -113,10 +156,10 @@ class Requests_Cookie {
 	/**
 	 * Check if a cookie is valid for a given URI
 	 *
-	 * @param Requests_IRI $uri URI to check
+	 * @param \WpOrg\Requests\Iri $uri URI to check
 	 * @return boolean Whether the cookie is valid for the given URI
 	 */
-	public function uri_matches(Requests_IRI $uri) {
+	public function uri_matches(Iri $uri) {
 		if (!$this->domain_matches($uri->host)) {
 			return false;
 		}
@@ -131,19 +174,23 @@ class Requests_Cookie {
 	/**
 	 * Check if a cookie is valid for a given domain
 	 *
-	 * @param string $string Domain to check
+	 * @param string $domain Domain to check
 	 * @return boolean Whether the cookie is valid for the given domain
 	 */
-	public function domain_matches($string) {
+	public function domain_matches($domain) {
+		if (is_string($domain) === false) {
+			return false;
+		}
+
 		if (!isset($this->attributes['domain'])) {
 			// Cookies created manually; cookies created by Requests will set
 			// the domain to the requested domain
 			return true;
 		}
 
-		$domain_string = $this->attributes['domain'];
-		if ($domain_string === $string) {
-			// The domain string and the string are identical.
+		$cookie_domain = $this->attributes['domain'];
+		if ($cookie_domain === $domain) {
+			// The cookie domain and the passed domain are identical.
 			return true;
 		}
 
@@ -153,26 +200,26 @@ class Requests_Cookie {
 			return false;
 		}
 
-		if (strlen($string) <= strlen($domain_string)) {
-			// For obvious reasons, the string cannot be a suffix if the domain
-			// is shorter than the domain string
+		if (strlen($domain) <= strlen($cookie_domain)) {
+			// For obvious reasons, the cookie domain cannot be a suffix if the passed domain
+			// is shorter than the cookie domain
 			return false;
 		}
 
-		if (substr($string, -1 * strlen($domain_string)) !== $domain_string) {
-			// The domain string should be a suffix of the string.
+		if (substr($domain, -1 * strlen($cookie_domain)) !== $cookie_domain) {
+			// The cookie domain should be a suffix of the passed domain.
 			return false;
 		}
 
-		$prefix = substr($string, 0, strlen($string) - strlen($domain_string));
+		$prefix = substr($domain, 0, strlen($domain) - strlen($cookie_domain));
 		if (substr($prefix, -1) !== '.') {
-			// The last character of the string that is not included in the
+			// The last character of the passed domain that is not included in the
 			// domain string should be a %x2E (".") character.
 			return false;
 		}
 
-		// The string should be a host name (i.e., not an IP address).
-		return !preg_match('#^(.+\.)\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$#', $string);
+		// The passed domain should be a host name (i.e., not an IP address).
+		return !preg_match('#^(.+\.)\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$#', $domain);
 	}
 
 	/**
@@ -195,6 +242,10 @@ class Requests_Cookie {
 			return true;
 		}
 
+		if (is_scalar($request_path) === false) {
+			return false;
+		}
+
 		$cookie_path = $this->attributes['path'];
 
 		if ($cookie_path === $request_path) {
@@ -280,8 +331,7 @@ class Requests_Cookie {
 				$delta_seconds = (int) $value;
 				if ($delta_seconds <= 0) {
 					$expiry_time = 0;
-				}
-				else {
+				} else {
 					$expiry_time = $this->reference_time + $delta_seconds;
 				}
 
@@ -316,17 +366,6 @@ class Requests_Cookie {
 		return sprintf('%s=%s', $this->name, $this->value);
 	}
 
-	/**
-	 * Format a cookie for a Cookie header
-	 *
-	 * @codeCoverageIgnore
-	 * @deprecated Use {@see Requests_Cookie::format_for_header}
-	 * @return string
-	 */
-	public function formatForHeader() {
-		return $this->format_for_header();
-	}
-
 	/**
 	 * Format a cookie for a Set-Cookie header
 	 *
@@ -338,42 +377,22 @@ class Requests_Cookie {
 	public function format_for_set_cookie() {
 		$header_value = $this->format_for_header();
 		if (!empty($this->attributes)) {
-			$parts = array();
+			$parts = [];
 			foreach ($this->attributes as $key => $value) {
 				// Ignore non-associative attributes
 				if (is_numeric($key)) {
 					$parts[] = $value;
-				}
-				else {
+				} else {
 					$parts[] = sprintf('%s=%s', $key, $value);
 				}
 			}
 
 			$header_value .= '; ' . implode('; ', $parts);
 		}
+
 		return $header_value;
 	}
 
-	/**
-	 * Format a cookie for a Set-Cookie header
-	 *
-	 * @codeCoverageIgnore
-	 * @deprecated Use {@see Requests_Cookie::format_for_set_cookie}
-	 * @return string
-	 */
-	public function formatForSetCookie() {
-		return $this->format_for_set_cookie();
-	}
-
-	/**
-	 * Get the cookie value
-	 *
-	 * Attributes and other data can be accessed via methods.
-	 */
-	public function __toString() {
-		return $this->value;
-	}
-
 	/**
 	 * Parse a cookie string into a cookie object
 	 *
@@ -381,17 +400,29 @@ class Requests_Cookie {
 	 * is an intentional deviation from RFC 2109 and RFC 2616. RFC 6265
 	 * specifies some of this handling, but not in a thorough manner.
 	 *
-	 * @param string Cookie header value (from a Set-Cookie header)
-	 * @return Requests_Cookie Parsed cookie object
+	 * @param string $cookie_header Cookie header value (from a Set-Cookie header)
+	 * @param string $name
+	 * @param int|null $reference_time
+	 * @return \WpOrg\Requests\Cookie Parsed cookie object
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $cookie_header argument is not a string.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $name argument is not a string.
 	 */
-	public static function parse($string, $name = '', $reference_time = null) {
-		$parts   = explode(';', $string);
+	public static function parse($cookie_header, $name = '', $reference_time = null) {
+		if (is_string($cookie_header) === false) {
+			throw InvalidArgument::create(1, '$cookie_header', 'string', gettype($cookie_header));
+		}
+
+		if (is_string($name) === false) {
+			throw InvalidArgument::create(2, '$name', 'string', gettype($name));
+		}
+
+		$parts   = explode(';', $cookie_header);
 		$kvparts = array_shift($parts);
 
 		if (!empty($name)) {
-			$value = $string;
-		}
-		elseif (strpos($kvparts, '=') === false) {
+			$value = $cookie_header;
+		} elseif (strpos($kvparts, '=') === false) {
 			// Some sites might only have a value without the equals separator.
 			// Deviate from RFC 6265 and pretend it was actually a blank name
 			// (`=foo`)
@@ -399,23 +430,22 @@ class Requests_Cookie {
 			// https://bugzilla.mozilla.org/show_bug.cgi?id=169091
 			$name  = '';
 			$value = $kvparts;
-		}
-		else {
+		} else {
 			list($name, $value) = explode('=', $kvparts, 2);
 		}
+
 		$name  = trim($name);
 		$value = trim($value);
 
-		// Attribute key are handled case-insensitively
-		$attributes = new Requests_Utility_CaseInsensitiveDictionary();
+		// Attribute keys are handled case-insensitively
+		$attributes = new CaseInsensitiveDictionary();
 
 		if (!empty($parts)) {
 			foreach ($parts as $part) {
 				if (strpos($part, '=') === false) {
 					$part_key   = $part;
 					$part_value = true;
-				}
-				else {
+				} else {
 					list($part_key, $part_value) = explode('=', $part, 2);
 					$part_value                  = trim($part_value);
 				}
@@ -425,24 +455,24 @@ class Requests_Cookie {
 			}
 		}
 
-		return new Requests_Cookie($name, $value, $attributes, array(), $reference_time);
+		return new static($name, $value, $attributes, [], $reference_time);
 	}
 
 	/**
 	 * Parse all Set-Cookie headers from request headers
 	 *
-	 * @param Requests_Response_Headers $headers Headers to parse from
-	 * @param Requests_IRI|null $origin URI for comparing cookie origins
+	 * @param \WpOrg\Requests\Response\Headers $headers Headers to parse from
+	 * @param \WpOrg\Requests\Iri|null $origin URI for comparing cookie origins
 	 * @param int|null $time Reference time for expiration calculation
 	 * @return array
 	 */
-	public static function parse_from_headers(Requests_Response_Headers $headers, Requests_IRI $origin = null, $time = null) {
+	public static function parse_from_headers(Headers $headers, Iri $origin = null, $time = null) {
 		$cookie_headers = $headers->getValues('Set-Cookie');
 		if (empty($cookie_headers)) {
-			return array();
+			return [];
 		}
 
-		$cookies = array();
+		$cookies = [];
 		foreach ($cookie_headers as $header) {
 			$parsed = self::parse($header, '', $time);
 
@@ -450,8 +480,7 @@ class Requests_Cookie {
 			if (empty($parsed->attributes['domain']) && !empty($origin)) {
 				$parsed->attributes['domain'] = $origin->host;
 				$parsed->flags['host-only']   = true;
-			}
-			else {
+			} else {
 				$parsed->flags['host-only'] = false;
 			}
 
@@ -465,19 +494,18 @@ class Requests_Cookie {
 					// the uri-path is not a %x2F ("/") character, output
 					// %x2F ("/") and skip the remaining steps.
 					$path = '/';
-				}
-				elseif (substr_count($path, '/') === 1) {
+				} elseif (substr_count($path, '/') === 1) {
 					// If the uri-path contains no more than one %x2F ("/")
 					// character, output %x2F ("/") and skip the remaining
 					// step.
 					$path = '/';
-				}
-				else {
+				} else {
 					// Output the characters of the uri-path from the first
 					// character up to, but not including, the right-most
 					// %x2F ("/").
 					$path = substr($path, 0, strrpos($path, '/'));
 				}
+
 				$parsed->attributes['path'] = $path;
 			}
 
@@ -491,15 +519,4 @@ class Requests_Cookie {
 
 		return $cookies;
 	}
-
-	/**
-	 * Parse all Set-Cookie headers from request headers
-	 *
-	 * @codeCoverageIgnore
-	 * @deprecated Use {@see Requests_Cookie::parse_from_headers}
-	 * @return array
-	 */
-	public static function parseFromHeaders(Requests_Response_Headers $headers) {
-		return self::parse_from_headers($headers);
-	}
 }
diff --git a/wp-includes/Requests/src/Cookie/Jar.php b/wp-includes/Requests/src/Cookie/Jar.php
new file mode 100644
index 0000000000..dfbb8b739b
--- /dev/null
+++ b/wp-includes/Requests/src/Cookie/Jar.php
@@ -0,0 +1,186 @@
+<?php
+/**
+ * Cookie holder object
+ *
+ * @package Requests\Cookies
+ */
+
+namespace WpOrg\Requests\Cookie;
+
+use ArrayAccess;
+use ArrayIterator;
+use IteratorAggregate;
+use ReturnTypeWillChange;
+use WpOrg\Requests\Cookie;
+use WpOrg\Requests\Exception;
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\HookManager;
+use WpOrg\Requests\Iri;
+use WpOrg\Requests\Response;
+
+/**
+ * Cookie holder object
+ *
+ * @package Requests\Cookies
+ */
+class Jar implements ArrayAccess, IteratorAggregate {
+	/**
+	 * Actual item data
+	 *
+	 * @var array
+	 */
+	protected $cookies = [];
+
+	/**
+	 * Create a new jar
+	 *
+	 * @param array $cookies Existing cookie values
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not an array.
+	 */
+	public function __construct($cookies = []) {
+		if (is_array($cookies) === false) {
+			throw InvalidArgument::create(1, '$cookies', 'array', gettype($cookies));
+		}
+
+		$this->cookies = $cookies;
+	}
+
+	/**
+	 * Normalise cookie data into a \WpOrg\Requests\Cookie
+	 *
+	 * @param string|\WpOrg\Requests\Cookie $cookie
+	 * @return \WpOrg\Requests\Cookie
+	 */
+	public function normalize_cookie($cookie, $key = '') {
+		if ($cookie instanceof Cookie) {
+			return $cookie;
+		}
+
+		return Cookie::parse($cookie, $key);
+	}
+
+	/**
+	 * Check if the given item exists
+	 *
+	 * @param string $offset Item key
+	 * @return boolean Does the item exist?
+	 */
+	#[ReturnTypeWillChange]
+	public function offsetExists($offset) {
+		return isset($this->cookies[$offset]);
+	}
+
+	/**
+	 * Get the value for the item
+	 *
+	 * @param string $offset Item key
+	 * @return string|null Item value (null if offsetExists is false)
+	 */
+	#[ReturnTypeWillChange]
+	public function offsetGet($offset) {
+		if (!isset($this->cookies[$offset])) {
+			return null;
+		}
+
+		return $this->cookies[$offset];
+	}
+
+	/**
+	 * Set the given item
+	 *
+	 * @param string $offset Item name
+	 * @param string $value Item value
+	 *
+	 * @throws \WpOrg\Requests\Exception On attempting to use dictionary as list (`invalidset`)
+	 */
+	#[ReturnTypeWillChange]
+	public function offsetSet($offset, $value) {
+		if ($offset === null) {
+			throw new Exception('Object is a dictionary, not a list', 'invalidset');
+		}
+
+		$this->cookies[$offset] = $value;
+	}
+
+	/**
+	 * Unset the given header
+	 *
+	 * @param string $offset
+	 */
+	#[ReturnTypeWillChange]
+	public function offsetUnset($offset) {
+		unset($this->cookies[$offset]);
+	}
+
+	/**
+	 * Get an iterator for the data
+	 *
+	 * @return \ArrayIterator
+	 */
+	#[ReturnTypeWillChange]
+	public function getIterator() {
+		return new ArrayIterator($this->cookies);
+	}
+
+	/**
+	 * Register the cookie handler with the request's hooking system
+	 *
+	 * @param \WpOrg\Requests\HookManager $hooks Hooking system
+	 */
+	public function register(HookManager $hooks) {
+		$hooks->register('requests.before_request', [$this, 'before_request']);
+		$hooks->register('requests.before_redirect_check', [$this, 'before_redirect_check']);
+	}
+
+	/**
+	 * Add Cookie header to a request if we have any
+	 *
+	 * As per RFC 6265, cookies are separated by '; '
+	 *
+	 * @param string $url
+	 * @param array $headers
+	 * @param array $data
+	 * @param string $type
+	 * @param array $options
+	 */
+	public function before_request($url, &$headers, &$data, &$type, &$options) {
+		if (!$url instanceof Iri) {
+			$url = new Iri($url);
+		}
+
+		if (!empty($this->cookies)) {
+			$cookies = [];
+			foreach ($this->cookies as $key => $cookie) {
+				$cookie = $this->normalize_cookie($cookie, $key);
+
+				// Skip expired cookies
+				if ($cookie->is_expired()) {
+					continue;
+				}
+
+				if ($cookie->domain_matches($url->host)) {
+					$cookies[] = $cookie->format_for_header();
+				}
+			}
+
+			$headers['Cookie'] = implode('; ', $cookies);
+		}
+	}
+
+	/**
+	 * Parse all cookies from a response and attach them to the response
+	 *
+	 * @param \WpOrg\Requests\Response $response
+	 */
+	public function before_redirect_check(Response $response) {
+		$url = $response->url;
+		if (!$url instanceof Iri) {
+			$url = new Iri($url);
+		}
+
+		$cookies           = Cookie::parse_from_headers($response->headers, $url);
+		$this->cookies     = array_merge($this->cookies, $cookies);
+		$response->cookies = $this;
+	}
+}
diff --git a/wp-includes/Requests/Exception.php b/wp-includes/Requests/src/Exception.php
similarity index 80%
rename from wp-includes/Requests/Exception.php
rename to wp-includes/Requests/src/Exception.php
index 1080efd971..b67d1b1a40 100644
--- a/wp-includes/Requests/Exception.php
+++ b/wp-includes/Requests/src/Exception.php
@@ -2,15 +2,19 @@
 /**
  * Exception for HTTP requests
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests;
+
+use Exception as PHPException;
+
 /**
  * Exception for HTTP requests
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception extends Exception {
+class Exception extends PHPException {
 	/**
 	 * Type of exception
 	 *
@@ -41,7 +45,7 @@ class Requests_Exception extends Exception {
 	}
 
 	/**
-	 * Like {@see getCode()}, but a string code.
+	 * Like {@see \Exception::getCode()}, but a string code.
 	 *
 	 * @codeCoverageIgnore
 	 * @return string
diff --git a/wp-includes/Requests/src/Exception/ArgumentCount.php b/wp-includes/Requests/src/Exception/ArgumentCount.php
new file mode 100644
index 0000000000..b5773ddf33
--- /dev/null
+++ b/wp-includes/Requests/src/Exception/ArgumentCount.php
@@ -0,0 +1,47 @@
+<?php
+
+namespace WpOrg\Requests\Exception;
+
+use WpOrg\Requests\Exception;
+
+/**
+ * Exception for when an incorrect number of arguments are passed to a method.
+ *
+ * Typically, this exception is used when all arguments for a method are optional,
+ * but certain arguments need to be passed together, i.e. a method which can be called
+ * with no arguments or with two arguments, but not with one argument.
+ *
+ * Along the same lines, this exception is also used if a method expects an array
+ * with a certain number of elements and the provided number of elements does not comply.
+ *
+ * @package Requests\Exceptions
+ * @since   2.0.0
+ */
+final class ArgumentCount extends Exception {
+
+	/**
+	 * Create a new argument count exception with a standardized text.
+	 *
+	 * @param string $expected The argument count expected as a phrase.
+	 *                         For example: `at least 2 arguments` or `exactly 1 argument`.
+	 * @param int    $received The actual argument count received.
+	 * @param string $type     Exception type.
+	 *
+	 * @return \WpOrg\Requests\Exception\ArgumentCount
+	 */
+	public static function create($expected, $received, $type) {
+		// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_debug_backtrace
+		$stack = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 2);
+
+		return new self(
+			sprintf(
+				'%s::%s() expects %s, %d given',
+				$stack[1]['class'],
+				$stack[1]['function'],
+				$expected,
+				$received
+			),
+			$type
+		);
+	}
+}
diff --git a/wp-includes/Requests/Exception/HTTP.php b/wp-includes/Requests/src/Exception/Http.php
similarity index 74%
rename from wp-includes/Requests/Exception/HTTP.php
rename to wp-includes/Requests/src/Exception/Http.php
index 42ac59095a..7efbc939dc 100644
--- a/wp-includes/Requests/Exception/HTTP.php
+++ b/wp-includes/Requests/src/Exception/Http.php
@@ -2,15 +2,20 @@
 /**
  * Exception based on HTTP response
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception;
+
+use WpOrg\Requests\Exception;
+use WpOrg\Requests\Exception\Http\StatusUnknown;
+
 /**
  * Exception based on HTTP response
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP extends Requests_Exception {
+class Http extends Exception {
 	/**
 	 * HTTP status code
 	 *
@@ -44,7 +49,9 @@ class Requests_Exception_HTTP extends Requests_Exception {
 	}
 
 	/**
-	 * Get the status message
+	 * Get the status message.
+	 *
+	 * @return string
 	 */
 	public function getReason() {
 		return $this->reason;
@@ -58,14 +65,14 @@ class Requests_Exception_HTTP extends Requests_Exception {
 	 */
 	public static function get_class($code) {
 		if (!$code) {
-			return 'Requests_Exception_HTTP_Unknown';
+			return StatusUnknown::class;
 		}
 
-		$class = sprintf('Requests_Exception_HTTP_%d', $code);
+		$class = sprintf('\WpOrg\Requests\Exception\Http\Status%d', $code);
 		if (class_exists($class)) {
 			return $class;
 		}
 
-		return 'Requests_Exception_HTTP_Unknown';
+		return StatusUnknown::class;
 	}
 }
diff --git a/wp-includes/Requests/Exception/HTTP/304.php b/wp-includes/Requests/src/Exception/Http/Status304.php
similarity index 61%
rename from wp-includes/Requests/Exception/HTTP/304.php
rename to wp-includes/Requests/src/Exception/Http/Status304.php
index 2636ba4517..d510ae7d4e 100644
--- a/wp-includes/Requests/Exception/HTTP/304.php
+++ b/wp-includes/Requests/src/Exception/Http/Status304.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 304 Not Modified responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 304 Not Modified responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_304 extends Requests_Exception_HTTP {
+final class Status304 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/305.php b/wp-includes/Requests/src/Exception/Http/Status305.php
similarity index 60%
rename from wp-includes/Requests/Exception/HTTP/305.php
rename to wp-includes/Requests/src/Exception/Http/Status305.php
index 37d115a81a..8be63c3f21 100644
--- a/wp-includes/Requests/Exception/HTTP/305.php
+++ b/wp-includes/Requests/src/Exception/Http/Status305.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 305 Use Proxy responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 305 Use Proxy responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_305 extends Requests_Exception_HTTP {
+final class Status305 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/306.php b/wp-includes/Requests/src/Exception/Http/Status306.php
similarity index 61%
rename from wp-includes/Requests/Exception/HTTP/306.php
rename to wp-includes/Requests/src/Exception/Http/Status306.php
index 743a4ed1d0..2f3534ab9d 100644
--- a/wp-includes/Requests/Exception/HTTP/306.php
+++ b/wp-includes/Requests/src/Exception/Http/Status306.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 306 Switch Proxy responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 306 Switch Proxy responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_306 extends Requests_Exception_HTTP {
+final class Status306 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/400.php b/wp-includes/Requests/src/Exception/Http/Status400.php
similarity index 60%
rename from wp-includes/Requests/Exception/HTTP/400.php
rename to wp-includes/Requests/src/Exception/Http/Status400.php
index 5bd5428c0f..4e39623578 100644
--- a/wp-includes/Requests/Exception/HTTP/400.php
+++ b/wp-includes/Requests/src/Exception/Http/Status400.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 400 Bad Request responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 400 Bad Request responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_400 extends Requests_Exception_HTTP {
+final class Status400 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/401.php b/wp-includes/Requests/src/Exception/Http/Status401.php
similarity index 61%
rename from wp-includes/Requests/Exception/HTTP/401.php
rename to wp-includes/Requests/src/Exception/Http/Status401.php
index 62a283ab09..2a76429ce7 100644
--- a/wp-includes/Requests/Exception/HTTP/401.php
+++ b/wp-includes/Requests/src/Exception/Http/Status401.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 401 Unauthorized responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 401 Unauthorized responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_401 extends Requests_Exception_HTTP {
+final class Status401 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/402.php b/wp-includes/Requests/src/Exception/Http/Status402.php
similarity index 62%
rename from wp-includes/Requests/Exception/HTTP/402.php
rename to wp-includes/Requests/src/Exception/Http/Status402.php
index f287fd4b22..09d42879d5 100644
--- a/wp-includes/Requests/Exception/HTTP/402.php
+++ b/wp-includes/Requests/src/Exception/Http/Status402.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 402 Payment Required responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 402 Payment Required responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_402 extends Requests_Exception_HTTP {
+final class Status402 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/403.php b/wp-includes/Requests/src/Exception/Http/Status403.php
similarity index 60%
rename from wp-includes/Requests/Exception/HTTP/403.php
rename to wp-includes/Requests/src/Exception/Http/Status403.php
index 2ae1c44459..0b1fc3963d 100644
--- a/wp-includes/Requests/Exception/HTTP/403.php
+++ b/wp-includes/Requests/src/Exception/Http/Status403.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 403 Forbidden responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 403 Forbidden responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_403 extends Requests_Exception_HTTP {
+final class Status403 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/404.php b/wp-includes/Requests/src/Exception/Http/Status404.php
similarity index 60%
rename from wp-includes/Requests/Exception/HTTP/404.php
rename to wp-includes/Requests/src/Exception/Http/Status404.php
index e6e28672c3..ef39a853e3 100644
--- a/wp-includes/Requests/Exception/HTTP/404.php
+++ b/wp-includes/Requests/src/Exception/Http/Status404.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 404 Not Found responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 404 Not Found responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_404 extends Requests_Exception_HTTP {
+final class Status404 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/405.php b/wp-includes/Requests/src/Exception/Http/Status405.php
similarity index 62%
rename from wp-includes/Requests/Exception/HTTP/405.php
rename to wp-includes/Requests/src/Exception/Http/Status405.php
index 0461e6108c..666fbfe7c7 100644
--- a/wp-includes/Requests/Exception/HTTP/405.php
+++ b/wp-includes/Requests/src/Exception/Http/Status405.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 405 Method Not Allowed responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 405 Method Not Allowed responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_405 extends Requests_Exception_HTTP {
+final class Status405 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/406.php b/wp-includes/Requests/src/Exception/Http/Status406.php
similarity index 61%
rename from wp-includes/Requests/Exception/HTTP/406.php
rename to wp-includes/Requests/src/Exception/Http/Status406.php
index 980ef0efc5..37952f80a2 100644
--- a/wp-includes/Requests/Exception/HTTP/406.php
+++ b/wp-includes/Requests/src/Exception/Http/Status406.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 406 Not Acceptable responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 406 Not Acceptable responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_406 extends Requests_Exception_HTTP {
+final class Status406 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/407.php b/wp-includes/Requests/src/Exception/Http/Status407.php
similarity index 64%
rename from wp-includes/Requests/Exception/HTTP/407.php
rename to wp-includes/Requests/src/Exception/Http/Status407.php
index d08c6af7cc..d8796f9b54 100644
--- a/wp-includes/Requests/Exception/HTTP/407.php
+++ b/wp-includes/Requests/src/Exception/Http/Status407.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 407 Proxy Authentication Required responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 407 Proxy Authentication Required responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_407 extends Requests_Exception_HTTP {
+final class Status407 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/408.php b/wp-includes/Requests/src/Exception/Http/Status408.php
similarity index 61%
rename from wp-includes/Requests/Exception/HTTP/408.php
rename to wp-includes/Requests/src/Exception/Http/Status408.php
index db15bc2910..6718d064a1 100644
--- a/wp-includes/Requests/Exception/HTTP/408.php
+++ b/wp-includes/Requests/src/Exception/Http/Status408.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 408 Request Timeout responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 408 Request Timeout responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_408 extends Requests_Exception_HTTP {
+final class Status408 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/409.php b/wp-includes/Requests/src/Exception/Http/Status409.php
similarity index 60%
rename from wp-includes/Requests/Exception/HTTP/409.php
rename to wp-includes/Requests/src/Exception/Http/Status409.php
index 83002f9361..711a5c43f7 100644
--- a/wp-includes/Requests/Exception/HTTP/409.php
+++ b/wp-includes/Requests/src/Exception/Http/Status409.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 409 Conflict responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 409 Conflict responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_409 extends Requests_Exception_HTTP {
+final class Status409 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/410.php b/wp-includes/Requests/src/Exception/Http/Status410.php
similarity index 58%
rename from wp-includes/Requests/Exception/HTTP/410.php
rename to wp-includes/Requests/src/Exception/Http/Status410.php
index 5bf7aa6d46..127443b781 100644
--- a/wp-includes/Requests/Exception/HTTP/410.php
+++ b/wp-includes/Requests/src/Exception/Http/Status410.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 410 Gone responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 410 Gone responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_410 extends Requests_Exception_HTTP {
+final class Status410 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/411.php b/wp-includes/Requests/src/Exception/Http/Status411.php
similarity index 61%
rename from wp-includes/Requests/Exception/HTTP/411.php
rename to wp-includes/Requests/src/Exception/Http/Status411.php
index 25517b4f36..e70e63c649 100644
--- a/wp-includes/Requests/Exception/HTTP/411.php
+++ b/wp-includes/Requests/src/Exception/Http/Status411.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 411 Length Required responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 411 Length Required responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_411 extends Requests_Exception_HTTP {
+final class Status411 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/412.php b/wp-includes/Requests/src/Exception/Http/Status412.php
similarity index 62%
rename from wp-includes/Requests/Exception/HTTP/412.php
rename to wp-includes/Requests/src/Exception/Http/Status412.php
index e89533a7ef..4a8b9185b2 100644
--- a/wp-includes/Requests/Exception/HTTP/412.php
+++ b/wp-includes/Requests/src/Exception/Http/Status412.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 412 Precondition Failed responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 412 Precondition Failed responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_412 extends Requests_Exception_HTTP {
+final class Status412 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/413.php b/wp-includes/Requests/src/Exception/Http/Status413.php
similarity index 63%
rename from wp-includes/Requests/Exception/HTTP/413.php
rename to wp-includes/Requests/src/Exception/Http/Status413.php
index a7b38fce11..96a96fb163 100644
--- a/wp-includes/Requests/Exception/HTTP/413.php
+++ b/wp-includes/Requests/src/Exception/Http/Status413.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 413 Request Entity Too Large responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 413 Request Entity Too Large responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_413 extends Requests_Exception_HTTP {
+final class Status413 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/414.php b/wp-includes/Requests/src/Exception/Http/Status414.php
similarity index 63%
rename from wp-includes/Requests/Exception/HTTP/414.php
rename to wp-includes/Requests/src/Exception/Http/Status414.php
index 54c8b8c9ae..b65ec937af 100644
--- a/wp-includes/Requests/Exception/HTTP/414.php
+++ b/wp-includes/Requests/src/Exception/Http/Status414.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 414 Request-URI Too Large responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 414 Request-URI Too Large responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_414 extends Requests_Exception_HTTP {
+final class Status414 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/415.php b/wp-includes/Requests/src/Exception/Http/Status415.php
similarity index 63%
rename from wp-includes/Requests/Exception/HTTP/415.php
rename to wp-includes/Requests/src/Exception/Http/Status415.php
index 6b5f0785b8..cb45655e97 100644
--- a/wp-includes/Requests/Exception/HTTP/415.php
+++ b/wp-includes/Requests/src/Exception/Http/Status415.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 415 Unsupported Media Type responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 415 Unsupported Media Type responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_415 extends Requests_Exception_HTTP {
+final class Status415 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/416.php b/wp-includes/Requests/src/Exception/Http/Status416.php
similarity index 65%
rename from wp-includes/Requests/Exception/HTTP/416.php
rename to wp-includes/Requests/src/Exception/Http/Status416.php
index 48a4ecdb8f..c3661a193c 100644
--- a/wp-includes/Requests/Exception/HTTP/416.php
+++ b/wp-includes/Requests/src/Exception/Http/Status416.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 416 Requested Range Not Satisfiable responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 416 Requested Range Not Satisfiable responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_416 extends Requests_Exception_HTTP {
+final class Status416 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/417.php b/wp-includes/Requests/src/Exception/Http/Status417.php
similarity index 62%
rename from wp-includes/Requests/Exception/HTTP/417.php
rename to wp-includes/Requests/src/Exception/Http/Status417.php
index 81570330aa..4adba9a23e 100644
--- a/wp-includes/Requests/Exception/HTTP/417.php
+++ b/wp-includes/Requests/src/Exception/Http/Status417.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 417 Expectation Failed responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 417 Expectation Failed responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_417 extends Requests_Exception_HTTP {
+final class Status417 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/418.php b/wp-includes/Requests/src/Exception/Http/Status418.php
similarity index 50%
rename from wp-includes/Requests/Exception/HTTP/418.php
rename to wp-includes/Requests/src/Exception/Http/Status418.php
index 0fcc87d614..5bcb2b84a9 100644
--- a/wp-includes/Requests/Exception/HTTP/418.php
+++ b/wp-includes/Requests/src/Exception/Http/Status418.php
@@ -2,17 +2,23 @@
 /**
  * Exception for 418 I'm A Teapot responses
  *
- * @see https://tools.ietf.org/html/rfc2324
- * @package Requests
+ * @link https://tools.ietf.org/html/rfc2324
+ *
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 418 I'm A Teapot responses
  *
- * @see https://tools.ietf.org/html/rfc2324
- * @package Requests
+ * @link https://tools.ietf.org/html/rfc2324
+ *
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_418 extends Requests_Exception_HTTP {
+final class Status418 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/428.php b/wp-includes/Requests/src/Exception/Http/Status428.php
similarity index 52%
rename from wp-includes/Requests/Exception/HTTP/428.php
rename to wp-includes/Requests/src/Exception/Http/Status428.php
index 799ddffd54..4d7ea51f5c 100644
--- a/wp-includes/Requests/Exception/HTTP/428.php
+++ b/wp-includes/Requests/src/Exception/Http/Status428.php
@@ -2,17 +2,23 @@
 /**
  * Exception for 428 Precondition Required responses
  *
- * @see https://tools.ietf.org/html/rfc6585
- * @package Requests
+ * @link https://tools.ietf.org/html/rfc6585
+ *
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 428 Precondition Required responses
  *
- * @see https://tools.ietf.org/html/rfc6585
- * @package Requests
+ * @link https://tools.ietf.org/html/rfc6585
+ *
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_428 extends Requests_Exception_HTTP {
+final class Status428 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/src/Exception/Http/Status429.php b/wp-includes/Requests/src/Exception/Http/Status429.php
new file mode 100644
index 0000000000..2018196c7b
--- /dev/null
+++ b/wp-includes/Requests/src/Exception/Http/Status429.php
@@ -0,0 +1,35 @@
+<?php
+/**
+ * Exception for 429 Too Many Requests responses
+ *
+ * @link https://tools.ietf.org/html/draft-nottingham-http-new-status-04
+ *
+ * @package Requests\Exceptions
+ */
+
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
+/**
+ * Exception for 429 Too Many Requests responses
+ *
+ * @link https://tools.ietf.org/html/draft-nottingham-http-new-status-04
+ *
+ * @package Requests\Exceptions
+ */
+final class Status429 extends Http {
+	/**
+	 * HTTP status code
+	 *
+	 * @var integer
+	 */
+	protected $code = 429;
+
+	/**
+	 * Reason phrase
+	 *
+	 * @var string
+	 */
+	protected $reason = 'Too Many Requests';
+}
diff --git a/wp-includes/Requests/Exception/HTTP/431.php b/wp-includes/Requests/src/Exception/Http/Status431.php
similarity index 55%
rename from wp-includes/Requests/Exception/HTTP/431.php
rename to wp-includes/Requests/src/Exception/Http/Status431.php
index a92b48a4e7..50bba430c7 100644
--- a/wp-includes/Requests/Exception/HTTP/431.php
+++ b/wp-includes/Requests/src/Exception/Http/Status431.php
@@ -2,17 +2,23 @@
 /**
  * Exception for 431 Request Header Fields Too Large responses
  *
- * @see https://tools.ietf.org/html/rfc6585
- * @package Requests
+ * @link https://tools.ietf.org/html/rfc6585
+ *
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 431 Request Header Fields Too Large responses
  *
- * @see https://tools.ietf.org/html/rfc6585
- * @package Requests
+ * @link https://tools.ietf.org/html/rfc6585
+ *
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_431 extends Requests_Exception_HTTP {
+final class Status431 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/500.php b/wp-includes/Requests/src/Exception/Http/Status500.php
similarity index 63%
rename from wp-includes/Requests/Exception/HTTP/500.php
rename to wp-includes/Requests/src/Exception/Http/Status500.php
index 22a6406ab2..42089ff0eb 100644
--- a/wp-includes/Requests/Exception/HTTP/500.php
+++ b/wp-includes/Requests/src/Exception/Http/Status500.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 500 Internal Server Error responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 500 Internal Server Error responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_500 extends Requests_Exception_HTTP {
+final class Status500 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/501.php b/wp-includes/Requests/src/Exception/Http/Status501.php
similarity index 61%
rename from wp-includes/Requests/Exception/HTTP/501.php
rename to wp-includes/Requests/src/Exception/Http/Status501.php
index 11f395b20a..2b924302bf 100644
--- a/wp-includes/Requests/Exception/HTTP/501.php
+++ b/wp-includes/Requests/src/Exception/Http/Status501.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 501 Not Implemented responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 501 Not Implemented responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_501 extends Requests_Exception_HTTP {
+final class Status501 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/502.php b/wp-includes/Requests/src/Exception/Http/Status502.php
similarity index 60%
rename from wp-includes/Requests/Exception/HTTP/502.php
rename to wp-includes/Requests/src/Exception/Http/Status502.php
index 43f576a625..7ce2b0f3de 100644
--- a/wp-includes/Requests/Exception/HTTP/502.php
+++ b/wp-includes/Requests/src/Exception/Http/Status502.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 502 Bad Gateway responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 502 Bad Gateway responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_502 extends Requests_Exception_HTTP {
+final class Status502 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/503.php b/wp-includes/Requests/src/Exception/Http/Status503.php
similarity index 62%
rename from wp-includes/Requests/Exception/HTTP/503.php
rename to wp-includes/Requests/src/Exception/Http/Status503.php
index 4024a4f5cd..2e70dd9286 100644
--- a/wp-includes/Requests/Exception/HTTP/503.php
+++ b/wp-includes/Requests/src/Exception/Http/Status503.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 503 Service Unavailable responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 503 Service Unavailable responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_503 extends Requests_Exception_HTTP {
+final class Status503 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/504.php b/wp-includes/Requests/src/Exception/Http/Status504.php
similarity index 61%
rename from wp-includes/Requests/Exception/HTTP/504.php
rename to wp-includes/Requests/src/Exception/Http/Status504.php
index 25fd08631c..efa100ae87 100644
--- a/wp-includes/Requests/Exception/HTTP/504.php
+++ b/wp-includes/Requests/src/Exception/Http/Status504.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 504 Gateway Timeout responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 504 Gateway Timeout responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_504 extends Requests_Exception_HTTP {
+final class Status504 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/505.php b/wp-includes/Requests/src/Exception/Http/Status505.php
similarity index 64%
rename from wp-includes/Requests/Exception/HTTP/505.php
rename to wp-includes/Requests/src/Exception/Http/Status505.php
index 1f7cfec9b5..71ba463207 100644
--- a/wp-includes/Requests/Exception/HTTP/505.php
+++ b/wp-includes/Requests/src/Exception/Http/Status505.php
@@ -2,15 +2,19 @@
 /**
  * Exception for 505 HTTP Version Not Supported responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 505 HTTP Version Not Supported responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_505 extends Requests_Exception_HTTP {
+final class Status505 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/511.php b/wp-includes/Requests/src/Exception/Http/Status511.php
similarity index 55%
rename from wp-includes/Requests/Exception/HTTP/511.php
rename to wp-includes/Requests/src/Exception/Http/Status511.php
index 3332513b15..8d6fee7b6a 100644
--- a/wp-includes/Requests/Exception/HTTP/511.php
+++ b/wp-includes/Requests/src/Exception/Http/Status511.php
@@ -2,17 +2,23 @@
 /**
  * Exception for 511 Network Authentication Required responses
  *
- * @see https://tools.ietf.org/html/rfc6585
- * @package Requests
+ * @link https://tools.ietf.org/html/rfc6585
+ *
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+
 /**
  * Exception for 511 Network Authentication Required responses
  *
- * @see https://tools.ietf.org/html/rfc6585
- * @package Requests
+ * @link https://tools.ietf.org/html/rfc6585
+ *
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_511 extends Requests_Exception_HTTP {
+final class Status511 extends Http {
 	/**
 	 * HTTP status code
 	 *
diff --git a/wp-includes/Requests/Exception/HTTP/Unknown.php b/wp-includes/Requests/src/Exception/Http/StatusUnknown.php
similarity index 61%
rename from wp-includes/Requests/Exception/HTTP/Unknown.php
rename to wp-includes/Requests/src/Exception/Http/StatusUnknown.php
index b7eeb79538..802793feeb 100644
--- a/wp-includes/Requests/Exception/HTTP/Unknown.php
+++ b/wp-includes/Requests/src/Exception/Http/StatusUnknown.php
@@ -2,15 +2,20 @@
 /**
  * Exception for unknown status responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
 
+namespace WpOrg\Requests\Exception\Http;
+
+use WpOrg\Requests\Exception\Http;
+use WpOrg\Requests\Response;
+
 /**
  * Exception for unknown status responses
  *
- * @package Requests
+ * @package Requests\Exceptions
  */
-class Requests_Exception_HTTP_Unknown extends Requests_Exception_HTTP {
+final class StatusUnknown extends Http {
 	/**
 	 * HTTP status code
 	 *
@@ -28,15 +33,15 @@ class Requests_Exception_HTTP_Unknown extends Requests_Exception_HTTP {
 	/**
 	 * Create a new exception
 	 *
-	 * If `$data` is an instance of {@see Requests_Response}, uses the status
+	 * If `$data` is an instance of {@see \WpOrg\Requests\Response}, uses the status
 	 * code from it. Otherwise, sets as 0
 	 *
 	 * @param string|null $reason Reason phrase
 	 * @param mixed $data Associated data
 	 */
 	public function __construct($reason = null, $data = null) {
-		if ($data instanceof Requests_Response) {
-			$this->code = $data->status_code;
+		if ($data instanceof Response) {
+			$this->code = (int) $data->status_code;
 		}
 
 		parent::__construct($reason, $data);
diff --git a/wp-includes/Requests/src/Exception/InvalidArgument.php b/wp-includes/Requests/src/Exception/InvalidArgument.php
new file mode 100644
index 0000000000..0ab7332f4f
--- /dev/null
+++ b/wp-includes/Requests/src/Exception/InvalidArgument.php
@@ -0,0 +1,41 @@
+<?php
+
+namespace WpOrg\Requests\Exception;
+
+use InvalidArgumentException;
+
+/**
+ * Exception for an invalid argument passed.
+ *
+ * @package Requests\Exceptions
+ * @since   2.0.0
+ */
+final class InvalidArgument extends InvalidArgumentException {
+
+	/**
+	 * Create a new invalid argument exception with a standardized text.
+	 *
+	 * @param int    $position The argument position in the function signature. 1-based.
+	 * @param string $name     The argument name in the function signature.
+	 * @param string $expected The argument type expected as a string.
+	 * @param string $received The actual argument type received.
+	 *
+	 * @return \WpOrg\Requests\Exception\InvalidArgument
+	 */
+	public static function create($position, $name, $expected, $received) {
+		// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_debug_backtrace
+		$stack = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 2);
+
+		return new self(
+			sprintf(
+				'%s::%s(): Argument #%d (%s) must be of type %s, %s given',
+				$stack[1]['class'],
+				$stack[1]['function'],
+				$position,
+				$name,
+				$expected,
+				$received
+			)
+		);
+	}
+}
diff --git a/wp-includes/Requests/src/Exception/Transport.php b/wp-includes/Requests/src/Exception/Transport.php
new file mode 100644
index 0000000000..c76e92ec1c
--- /dev/null
+++ b/wp-includes/Requests/src/Exception/Transport.php
@@ -0,0 +1,17 @@
+<?php
+/**
+ * Transport Exception
+ *
+ * @package Requests\Exceptions
+ */
+
+namespace WpOrg\Requests\Exception;
+
+use WpOrg\Requests\Exception;
+
+/**
+ * Transport Exception
+ *
+ * @package Requests\Exceptions
+ */
+class Transport extends Exception {}
diff --git a/wp-includes/Requests/Exception/Transport/cURL.php b/wp-includes/Requests/src/Exception/Transport/Curl.php
similarity index 56%
rename from wp-includes/Requests/Exception/Transport/cURL.php
rename to wp-includes/Requests/src/Exception/Transport/Curl.php
index fffa8c259b..4c0294d748 100644
--- a/wp-includes/Requests/Exception/Transport/cURL.php
+++ b/wp-includes/Requests/src/Exception/Transport/Curl.php
@@ -1,6 +1,20 @@
 <?php
+/**
+ * CURL Transport Exception.
+ *
+ * @package Requests\Exceptions
+ */
 
-class Requests_Exception_Transport_cURL extends Requests_Exception_Transport {
+namespace WpOrg\Requests\Exception\Transport;
+
+use WpOrg\Requests\Exception\Transport;
+
+/**
+ * CURL Transport Exception.
+ *
+ * @package Requests\Exceptions
+ */
+final class Curl extends Transport {
 
 	const EASY  = 'cURLEasy';
 	const MULTI = 'cURLMulti';
@@ -29,13 +43,21 @@ class Requests_Exception_Transport_cURL extends Requests_Exception_Transport {
 	 */
 	protected $reason = 'Unknown';
 
+	/**
+	 * Create a new exception.
+	 *
+	 * @param string $message Exception message.
+	 * @param string $type    Exception type.
+	 * @param mixed  $data    Associated data, if applicable.
+	 * @param int    $code    Exception numerical code, if applicable.
+	 */
 	public function __construct($message, $type, $data = null, $code = 0) {
 		if ($type !== null) {
 			$this->type = $type;
 		}
 
 		if ($code !== null) {
-			$this->code = $code;
+			$this->code = (int) $code;
 		}
 
 		if ($message !== null) {
@@ -47,7 +69,9 @@ class Requests_Exception_Transport_cURL extends Requests_Exception_Transport {
 	}
 
 	/**
-	 * Get the error message
+	 * Get the error message.
+	 *
+	 * @return string
 	 */
 	public function getReason() {
 		return $this->reason;
diff --git a/wp-includes/Requests/Hooker.php b/wp-includes/Requests/src/HookManager.php
similarity index 66%
rename from wp-includes/Requests/Hooker.php
rename to wp-includes/Requests/src/HookManager.php
index c852931f1a..f2920170b9 100644
--- a/wp-includes/Requests/Hooker.php
+++ b/wp-includes/Requests/src/HookManager.php
@@ -2,22 +2,22 @@
 /**
  * Event dispatcher
  *
- * @package Requests
- * @subpackage Utilities
+ * @package Requests\EventDispatcher
  */
 
+namespace WpOrg\Requests;
+
 /**
  * Event dispatcher
  *
- * @package Requests
- * @subpackage Utilities
+ * @package Requests\EventDispatcher
  */
-interface Requests_Hooker {
+interface HookManager {
 	/**
 	 * Register a callback for a hook
 	 *
 	 * @param string $hook Hook name
-	 * @param callback $callback Function/method to call on event
+	 * @param callable $callback Function/method to call on event
 	 * @param int $priority Priority number. <0 is executed earlier, >0 is executed later
 	 */
 	public function register($hook, $callback, $priority = 0);
@@ -29,5 +29,5 @@ interface Requests_Hooker {
 	 * @param array $parameters Parameters to pass to callbacks
 	 * @return boolean Successfulness
 	 */
-	public function dispatch($hook, $parameters = array());
+	public function dispatch($hook, $parameters = []);
 }
diff --git a/wp-includes/Requests/src/Hooks.php b/wp-includes/Requests/src/Hooks.php
new file mode 100644
index 0000000000..74fba0b3e1
--- /dev/null
+++ b/wp-includes/Requests/src/Hooks.php
@@ -0,0 +1,99 @@
+<?php
+/**
+ * Handles adding and dispatching events
+ *
+ * @package Requests\EventDispatcher
+ */
+
+namespace WpOrg\Requests;
+
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\HookManager;
+use WpOrg\Requests\Utility\InputValidator;
+
+/**
+ * Handles adding and dispatching events
+ *
+ * @package Requests\EventDispatcher
+ */
+class Hooks implements HookManager {
+	/**
+	 * Registered callbacks for each hook
+	 *
+	 * @var array
+	 */
+	protected $hooks = [];
+
+	/**
+	 * Register a callback for a hook
+	 *
+	 * @param string $hook Hook name
+	 * @param callable $callback Function/method to call on event
+	 * @param int $priority Priority number. <0 is executed earlier, >0 is executed later
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $hook argument is not a string.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $callback argument is not callable.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $priority argument is not an integer.
+	 */
+	public function register($hook, $callback, $priority = 0) {
+		if (is_string($hook) === false) {
+			throw InvalidArgument::create(1, '$hook', 'string', gettype($hook));
+		}
+
+		if (is_callable($callback) === false) {
+			throw InvalidArgument::create(2, '$callback', 'callable', gettype($callback));
+		}
+
+		if (InputValidator::is_numeric_array_key($priority) === false) {
+			throw InvalidArgument::create(3, '$priority', 'integer', gettype($priority));
+		}
+
+		if (!isset($this->hooks[$hook])) {
+			$this->hooks[$hook] = [
+				$priority => [],
+			];
+		} elseif (!isset($this->hooks[$hook][$priority])) {
+			$this->hooks[$hook][$priority] = [];
+		}
+
+		$this->hooks[$hook][$priority][] = $callback;
+	}
+
+	/**
+	 * Dispatch a message
+	 *
+	 * @param string $hook Hook name
+	 * @param array $parameters Parameters to pass to callbacks
+	 * @return boolean Successfulness
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $hook argument is not a string.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $parameters argument is not an array.
+	 */
+	public function dispatch($hook, $parameters = []) {
+		if (is_string($hook) === false) {
+			throw InvalidArgument::create(1, '$hook', 'string', gettype($hook));
+		}
+
+		// Check strictly against array, as Array* objects don't work in combination with `call_user_func_array()`.
+		if (is_array($parameters) === false) {
+			throw InvalidArgument::create(2, '$parameters', 'array', gettype($parameters));
+		}
+
+		if (empty($this->hooks[$hook])) {
+			return false;
+		}
+
+		if (!empty($parameters)) {
+			// Strip potential keys from the array to prevent them being interpreted as parameter names in PHP 8.0.
+			$parameters = array_values($parameters);
+		}
+
+		ksort($this->hooks[$hook]);
+
+		foreach ($this->hooks[$hook] as $priority => $hooked) {
+			foreach ($hooked as $callback) {
+				$callback(...$parameters);
+			}
+		}
+
+		return true;
+	}
+}
diff --git a/wp-includes/Requests/IDNAEncoder.php b/wp-includes/Requests/src/IdnaEncoder.php
similarity index 60%
rename from wp-includes/Requests/IDNAEncoder.php
rename to wp-includes/Requests/src/IdnaEncoder.php
index 881142935b..094fff3d52 100644
--- a/wp-includes/Requests/IDNAEncoder.php
+++ b/wp-includes/Requests/src/IdnaEncoder.php
@@ -1,28 +1,45 @@
 <?php
 
+namespace WpOrg\Requests;
+
+use WpOrg\Requests\Exception;
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Utility\InputValidator;
+
 /**
  * IDNA URL encoder
  *
  * Note: Not fully compliant, as nameprep does nothing yet.
  *
- * @package Requests
- * @subpackage Utilities
- * @see https://tools.ietf.org/html/rfc3490 IDNA specification
- * @see https://tools.ietf.org/html/rfc3492 Punycode/Bootstrap specification
+ * @package Requests\Utilities
+ *
+ * @link https://tools.ietf.org/html/rfc3490 IDNA specification
+ * @link https://tools.ietf.org/html/rfc3492 Punycode/Bootstrap specification
  */
-class Requests_IDNAEncoder {
+class IdnaEncoder {
 	/**
 	 * ACE prefix used for IDNA
 	 *
-	 * @see https://tools.ietf.org/html/rfc3490#section-5
+	 * @link https://tools.ietf.org/html/rfc3490#section-5
 	 * @var string
 	 */
 	const ACE_PREFIX = 'xn--';
 
+	/**
+	 * Maximum length of a IDNA URL in ASCII.
+	 *
+	 * @see \WpOrg\Requests\IdnaEncoder::to_ascii()
+	 *
+	 * @since 2.0.0
+	 *
+	 * @var int
+	 */
+	const MAX_LENGTH = 64;
+
 	/**#@+
 	 * Bootstrap constant for Punycode
 	 *
-	 * @see https://tools.ietf.org/html/rfc3492#section-5
+	 * @link https://tools.ietf.org/html/rfc3492#section-5
 	 * @var int
 	 */
 	const BOOTSTRAP_BASE         = 36;
@@ -37,106 +54,119 @@ class Requests_IDNAEncoder {
 	/**
 	 * Encode a hostname using Punycode
 	 *
-	 * @param string $string Hostname
+	 * @param string|Stringable $hostname Hostname
 	 * @return string Punycode-encoded hostname
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not a string or a stringable object.
 	 */
-	public static function encode($string) {
-		$parts = explode('.', $string);
+	public static function encode($hostname) {
+		if (InputValidator::is_string_or_stringable($hostname) === false) {
+			throw InvalidArgument::create(1, '$hostname', 'string|Stringable', gettype($hostname));
+		}
+
+		$parts = explode('.', $hostname);
 		foreach ($parts as &$part) {
 			$part = self::to_ascii($part);
 		}
+
 		return implode('.', $parts);
 	}
 
 	/**
-	 * Convert a UTF-8 string to an ASCII string using Punycode
+	 * Convert a UTF-8 text string to an ASCII string using Punycode
 	 *
-	 * @throws Requests_Exception Provided string longer than 64 ASCII characters (`idna.provided_too_long`)
-	 * @throws Requests_Exception Prepared string longer than 64 ASCII characters (`idna.prepared_too_long`)
-	 * @throws Requests_Exception Provided string already begins with xn-- (`idna.provided_is_prefixed`)
-	 * @throws Requests_Exception Encoded string longer than 64 ASCII characters (`idna.encoded_too_long`)
-	 *
-	 * @param string $string ASCII or UTF-8 string (max length 64 characters)
+	 * @param string $text ASCII or UTF-8 string (max length 64 characters)
 	 * @return string ASCII string
+	 *
+	 * @throws \WpOrg\Requests\Exception Provided string longer than 64 ASCII characters (`idna.provided_too_long`)
+	 * @throws \WpOrg\Requests\Exception Prepared string longer than 64 ASCII characters (`idna.prepared_too_long`)
+	 * @throws \WpOrg\Requests\Exception Provided string already begins with xn-- (`idna.provided_is_prefixed`)
+	 * @throws \WpOrg\Requests\Exception Encoded string longer than 64 ASCII characters (`idna.encoded_too_long`)
 	 */
-	public static function to_ascii($string) {
-		// Step 1: Check if the string is already ASCII
-		if (self::is_ascii($string)) {
+	public static function to_ascii($text) {
+		// Step 1: Check if the text is already ASCII
+		if (self::is_ascii($text)) {
 			// Skip to step 7
-			if (strlen($string) < 64) {
-				return $string;
+			if (strlen($text) < self::MAX_LENGTH) {
+				return $text;
 			}
 
-			throw new Requests_Exception('Provided string is too long', 'idna.provided_too_long', $string);
+			throw new Exception('Provided string is too long', 'idna.provided_too_long', $text);
 		}
 
 		// Step 2: nameprep
-		$string = self::nameprep($string);
+		$text = self::nameprep($text);
 
 		// Step 3: UseSTD3ASCIIRules is false, continue
 		// Step 4: Check if it's ASCII now
-		if (self::is_ascii($string)) {
+		if (self::is_ascii($text)) {
 			// Skip to step 7
-			if (strlen($string) < 64) {
-				return $string;
+			/*
+			 * As the `nameprep()` method returns the original string, this code will never be reached until
+			 * that method is properly implemented.
+			 */
+			// @codeCoverageIgnoreStart
+			if (strlen($text) < self::MAX_LENGTH) {
+				return $text;
 			}
 
-			throw new Requests_Exception('Prepared string is too long', 'idna.prepared_too_long', $string);
+			throw new Exception('Prepared string is too long', 'idna.prepared_too_long', $text);
+			// @codeCoverageIgnoreEnd
 		}
 
 		// Step 5: Check ACE prefix
-		if (strpos($string, self::ACE_PREFIX) === 0) {
-			throw new Requests_Exception('Provided string begins with ACE prefix', 'idna.provided_is_prefixed', $string);
+		if (strpos($text, self::ACE_PREFIX) === 0) {
+			throw new Exception('Provided string begins with ACE prefix', 'idna.provided_is_prefixed', $text);
 		}
 
 		// Step 6: Encode with Punycode
-		$string = self::punycode_encode($string);
+		$text = self::punycode_encode($text);
 
 		// Step 7: Prepend ACE prefix
-		$string = self::ACE_PREFIX . $string;
+		$text = self::ACE_PREFIX . $text;
 
 		// Step 8: Check size
-		if (strlen($string) < 64) {
-			return $string;
+		if (strlen($text) < self::MAX_LENGTH) {
+			return $text;
 		}
 
-		throw new Requests_Exception('Encoded string is too long', 'idna.encoded_too_long', $string);
+		throw new Exception('Encoded string is too long', 'idna.encoded_too_long', $text);
 	}
 
 	/**
-	 * Check whether a given string contains only ASCII characters
+	 * Check whether a given text string contains only ASCII characters
 	 *
 	 * @internal (Testing found regex was the fastest implementation)
 	 *
-	 * @param string $string
-	 * @return bool Is the string ASCII-only?
+	 * @param string $text
+	 * @return bool Is the text string ASCII-only?
 	 */
-	protected static function is_ascii($string) {
-		return (preg_match('/(?:[^\x00-\x7F])/', $string) !== 1);
+	protected static function is_ascii($text) {
+		return (preg_match('/(?:[^\x00-\x7F])/', $text) !== 1);
 	}
 
 	/**
-	 * Prepare a string for use as an IDNA name
+	 * Prepare a text string for use as an IDNA name
 	 *
 	 * @todo Implement this based on RFC 3491 and the newer 5891
-	 * @param string $string
+	 * @param string $text
 	 * @return string Prepared string
 	 */
-	protected static function nameprep($string) {
-		return $string;
+	protected static function nameprep($text) {
+		return $text;
 	}
 
 	/**
 	 * Convert a UTF-8 string to a UCS-4 codepoint array
 	 *
-	 * Based on Requests_IRI::replace_invalid_with_pct_encoding()
+	 * Based on \WpOrg\Requests\Iri::replace_invalid_with_pct_encoding()
 	 *
-	 * @throws Requests_Exception Invalid UTF-8 codepoint (`idna.invalidcodepoint`)
 	 * @param string $input
 	 * @return array Unicode code points
+	 *
+	 * @throws \WpOrg\Requests\Exception Invalid UTF-8 codepoint (`idna.invalidcodepoint`)
 	 */
 	protected static function utf8_to_codepoints($input) {
-		$codepoints = array();
+		$codepoints = [];
 
 		// Get number of bytes
 		$strlen = strlen($input);
@@ -145,50 +175,43 @@ class Requests_IDNAEncoder {
 		for ($position = 0; $position < $strlen; $position++) {
 			$value = ord($input[$position]);
 
-			// One byte sequence:
-			if ((~$value & 0x80) === 0x80) {
+			if ((~$value & 0x80) === 0x80) {            // One byte sequence:
 				$character = $value;
 				$length    = 1;
 				$remaining = 0;
-			}
-			// Two byte sequence:
-			elseif (($value & 0xE0) === 0xC0) {
+			} elseif (($value & 0xE0) === 0xC0) {       // Two byte sequence:
 				$character = ($value & 0x1F) << 6;
 				$length    = 2;
 				$remaining = 1;
-			}
-			// Three byte sequence:
-			elseif (($value & 0xF0) === 0xE0) {
+			} elseif (($value & 0xF0) === 0xE0) {       // Three byte sequence:
 				$character = ($value & 0x0F) << 12;
 				$length    = 3;
 				$remaining = 2;
-			}
-			// Four byte sequence:
-			elseif (($value & 0xF8) === 0xF0) {
+			} elseif (($value & 0xF8) === 0xF0) {       // Four byte sequence:
 				$character = ($value & 0x07) << 18;
 				$length    = 4;
 				$remaining = 3;
-			}
-			// Invalid byte:
-			else {
-				throw new Requests_Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $value);
+			} else {                                    // Invalid byte:
+				throw new Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $value);
 			}
 
 			if ($remaining > 0) {
 				if ($position + $length > $strlen) {
-					throw new Requests_Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $character);
+					throw new Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $character);
 				}
+
 				for ($position++; $remaining > 0; $position++) {
 					$value = ord($input[$position]);
 
 					// If it is invalid, count the sequence as invalid and reprocess the current byte:
 					if (($value & 0xC0) !== 0x80) {
-						throw new Requests_Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $character);
+						throw new Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $character);
 					}
 
 					--$remaining;
 					$character |= ($value & 0x3F) << ($remaining * 6);
 				}
+
 				$position--;
 			}
 
@@ -208,7 +231,7 @@ class Requests_IDNAEncoder {
 					|| $character > 0xEFFFD
 				)
 			) {
-				throw new Requests_Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $character);
+				throw new Exception('Invalid Unicode codepoint', 'idna.invalidcodepoint', $character);
 			}
 
 			$codepoints[] = $character;
@@ -221,10 +244,11 @@ class Requests_IDNAEncoder {
 	 * RFC3492-compliant encoder
 	 *
 	 * @internal Pseudo-code from Section 6.3 is commented with "#" next to relevant code
-	 * @throws Requests_Exception On character outside of the domain (never happens with Punycode) (`idna.character_outside_domain`)
 	 *
 	 * @param string $input UTF-8 encoded string to encode
 	 * @return string Punycode-encoded string
+	 *
+	 * @throws \WpOrg\Requests\Exception On character outside of the domain (never happens with Punycode) (`idna.character_outside_domain`)
 	 */
 	public static function punycode_encode($input) {
 		$output = '';
@@ -239,7 +263,7 @@ class Requests_IDNAEncoder {
 		$b = 0; // see loop
 		// copy them to the output in order
 		$codepoints = self::utf8_to_codepoints($input);
-		$extended   = array();
+		$extended   = [];
 
 		foreach ($codepoints as $char) {
 			if ($char < 128) {
@@ -247,18 +271,18 @@ class Requests_IDNAEncoder {
 				// TODO: this should also check if it's valid for a URL
 				$output .= chr($char);
 				$h++;
-			}
-			// Check if the character is non-ASCII, but below initial n
-			// This never occurs for Punycode, so ignore in coverage
-			// @codeCoverageIgnoreStart
-			elseif ($char < $n) {
-				throw new Requests_Exception('Invalid character', 'idna.character_outside_domain', $char);
-			}
-			// @codeCoverageIgnoreEnd
-			else {
+
+				// Check if the character is non-ASCII, but below initial n
+				// This never occurs for Punycode, so ignore in coverage
+				// @codeCoverageIgnoreStart
+			} elseif ($char < $n) {
+				throw new Exception('Invalid character', 'idna.character_outside_domain', $char);
+				// @codeCoverageIgnoreEnd
+			} else {
 				$extended[$char] = true;
 			}
 		}
+
 		$extended = array_keys($extended);
 		sort($extended);
 		$b = $h;
@@ -266,6 +290,7 @@ class Requests_IDNAEncoder {
 		if (strlen($output) > 0) {
 			$output .= '-';
 		}
+
 		// {if the input contains a non-basic code point < n then fail}
 		// while h < length(input) do begin
 		$codepointcount = count($codepoints);
@@ -283,9 +308,7 @@ class Requests_IDNAEncoder {
 				// if c < n then increment delta, fail on overflow
 				if ($c < $n) {
 					$delta++;
-				}
-				// if c == n then begin
-				elseif ($c === $n) {
+				} elseif ($c === $n) { // if c == n then begin
 					// let q = delta
 					$q = $delta;
 					// for k = base to infinity in steps of base do begin
@@ -294,17 +317,17 @@ class Requests_IDNAEncoder {
 						//     tmax if k >= bias + tmax, or k - bias otherwise
 						if ($k <= ($bias + self::BOOTSTRAP_TMIN)) {
 							$t = self::BOOTSTRAP_TMIN;
-						}
-						elseif ($k >= ($bias + self::BOOTSTRAP_TMAX)) {
+						} elseif ($k >= ($bias + self::BOOTSTRAP_TMAX)) {
 							$t = self::BOOTSTRAP_TMAX;
-						}
-						else {
+						} else {
 							$t = $k - $bias;
 						}
+
 						// if q < t then break
 						if ($q < $t) {
 							break;
 						}
+
 						// output the code point for digit t + ((q - t) mod (base - t))
 						$digit   = $t + (($q - $t) % (self::BOOTSTRAP_BASE - $t));
 						$output .= self::digit_to_char($digit);
@@ -332,18 +355,20 @@ class Requests_IDNAEncoder {
 	/**
 	 * Convert a digit to its respective character
 	 *
-	 * @see https://tools.ietf.org/html/rfc3492#section-5
-	 * @throws Requests_Exception On invalid digit (`idna.invalid_digit`)
+	 * @link https://tools.ietf.org/html/rfc3492#section-5
 	 *
 	 * @param int $digit Digit in the range 0-35
 	 * @return string Single character corresponding to digit
+	 *
+	 * @throws \WpOrg\Requests\Exception On invalid digit (`idna.invalid_digit`)
 	 */
 	protected static function digit_to_char($digit) {
 		// @codeCoverageIgnoreStart
 		// As far as I know, this never happens, but still good to be sure.
 		if ($digit < 0 || $digit > 35) {
-			throw new Requests_Exception(sprintf('Invalid digit %d', $digit), 'idna.invalid_digit', $digit);
+			throw new Exception(sprintf('Invalid digit %d', $digit), 'idna.invalid_digit', $digit);
 		}
+
 		// @codeCoverageIgnoreEnd
 		$digits = 'abcdefghijklmnopqrstuvwxyz0123456789';
 		return substr($digits, $digit, 1);
@@ -352,7 +377,7 @@ class Requests_IDNAEncoder {
 	/**
 	 * Adapt the bias
 	 *
-	 * @see https://tools.ietf.org/html/rfc3492#section-6.1
+	 * @link https://tools.ietf.org/html/rfc3492#section-6.1
 	 * @param int $delta
 	 * @param int $numpoints
 	 * @param bool $firsttime
@@ -364,11 +389,11 @@ class Requests_IDNAEncoder {
 		// if firsttime then let delta = delta div damp
 		if ($firsttime) {
 			$delta = floor($delta / self::BOOTSTRAP_DAMP);
-		}
-		// else let delta = delta div 2
-		else {
+		} else {
+			// else let delta = delta div 2
 			$delta = floor($delta / 2);
 		}
+
 		// let delta = delta + (delta div numpoints)
 		$delta += floor($delta / $numpoints);
 		// let k = 0
diff --git a/wp-includes/Requests/IPv6.php b/wp-includes/Requests/src/Ipv6.php
similarity index 79%
rename from wp-includes/Requests/IPv6.php
rename to wp-includes/Requests/src/Ipv6.php
index ba88786be6..a90ab8a831 100644
--- a/wp-includes/Requests/IPv6.php
+++ b/wp-includes/Requests/src/Ipv6.php
@@ -2,20 +2,23 @@
 /**
  * Class to validate and to work with IPv6 addresses
  *
- * @package Requests
- * @subpackage Utilities
+ * @package Requests\Utilities
  */
 
+namespace WpOrg\Requests;
+
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Utility\InputValidator;
+
 /**
  * Class to validate and to work with IPv6 addresses
  *
  * This was originally based on the PEAR class of the same name, but has been
  * entirely rewritten.
  *
- * @package Requests
- * @subpackage Utilities
+ * @package Requests\Utilities
  */
-class Requests_IPv6 {
+final class Ipv6 {
 	/**
 	 * Uncompresses an IPv6 address
 	 *
@@ -30,11 +33,20 @@ class Requests_IPv6 {
 	 * @author elfrink at introweb dot nl
 	 * @author Josh Peck <jmp at joshpeck dot org>
 	 * @copyright 2003-2005 The PHP Group
-	 * @license http://www.opensource.org/licenses/bsd-license.php
-	 * @param string $ip An IPv6 address
+	 * @license https://opensource.org/licenses/bsd-license.php
+	 *
+	 * @param string|Stringable $ip An IPv6 address
 	 * @return string The uncompressed IPv6 address
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not a string or a stringable object.
 	 */
 	public static function uncompress($ip) {
+		if (InputValidator::is_string_or_stringable($ip) === false) {
+			throw InvalidArgument::create(1, '$ip', 'string|Stringable', gettype($ip));
+		}
+
+		$ip = (string) $ip;
+
 		if (substr_count($ip, '::') !== 1) {
 			return $ip;
 		}
@@ -46,25 +58,24 @@ class Requests_IPv6 {
 		if (strpos($ip2, '.') !== false) {
 			$c2++;
 		}
-		// ::
+
 		if ($c1 === -1 && $c2 === -1) {
+			// ::
 			$ip = '0:0:0:0:0:0:0:0';
-		}
-		// ::xxx
-		elseif ($c1 === -1) {
+		} elseif ($c1 === -1) {
+			// ::xxx
 			$fill = str_repeat('0:', 7 - $c2);
 			$ip   = str_replace('::', $fill, $ip);
-		}
-		// xxx::
-		elseif ($c2 === -1) {
+		} elseif ($c2 === -1) {
+			// xxx::
 			$fill = str_repeat(':0', 7 - $c1);
 			$ip   = str_replace('::', $fill, $ip);
-		}
-		// xxx::xxx
-		else {
+		} else {
+			// xxx::xxx
 			$fill = ':' . str_repeat('0:', 6 - $c2 - $c1);
 			$ip   = str_replace('::', $fill, $ip);
 		}
+
 		return $ip;
 	}
 
@@ -78,12 +89,14 @@ class Requests_IPv6 {
 	 * Example:  FF01:0:0:0:0:0:0:101   ->  FF01::101
 	 *           0:0:0:0:0:0:0:1        ->  ::1
 	 *
-	 * @see uncompress()
+	 * @see \WpOrg\Requests\Ipv6::uncompress()
+	 *
 	 * @param string $ip An IPv6 address
 	 * @return string The compressed IPv6 address
 	 */
 	public static function compress($ip) {
-		// Prepare the IP to be compressed
+		// Prepare the IP to be compressed.
+		// Note: Input validation is handled in the `uncompress()` method, which is the first call made in this method.
 		$ip       = self::uncompress($ip);
 		$ip_parts = self::split_v6_v4($ip);
 
@@ -106,8 +119,7 @@ class Requests_IPv6 {
 
 		if ($ip_parts[1] !== '') {
 			return implode(':', $ip_parts);
-		}
-		else {
+		} else {
 			return $ip_parts[0];
 		}
 	}
@@ -124,15 +136,14 @@ class Requests_IPv6 {
 	 * @param string $ip An IPv6 address
 	 * @return string[] [0] contains the IPv6 represented part, and [1] the IPv4 represented part
 	 */
-	protected static function split_v6_v4($ip) {
+	private static function split_v6_v4($ip) {
 		if (strpos($ip, '.') !== false) {
 			$pos       = strrpos($ip, ':');
 			$ipv6_part = substr($ip, 0, $pos);
 			$ipv4_part = substr($ip, $pos + 1);
-			return array($ipv6_part, $ipv4_part);
-		}
-		else {
-			return array($ip, '');
+			return [$ipv6_part, $ipv4_part];
+		} else {
+			return [$ip, ''];
 		}
 	}
 
@@ -145,6 +156,7 @@ class Requests_IPv6 {
 	 * @return bool true if $ip is a valid IPv6 address
 	 */
 	public static function check_ipv6($ip) {
+		// Note: Input validation is handled in the `uncompress()` method, which is the first call made in this method.
 		$ip                = self::uncompress($ip);
 		list($ipv6, $ipv4) = self::split_v6_v4($ip);
 		$ipv6              = explode(':', $ipv6);
@@ -173,6 +185,7 @@ class Requests_IPv6 {
 					return false;
 				}
 			}
+
 			if (count($ipv4) === 4) {
 				foreach ($ipv4 as $ipv4_part) {
 					$value = (int) $ipv4_part;
@@ -181,9 +194,9 @@ class Requests_IPv6 {
 					}
 				}
 			}
+
 			return true;
-		}
-		else {
+		} else {
 			return false;
 		}
 	}
diff --git a/wp-includes/Requests/IRI.php b/wp-includes/Requests/src/Iri.php
similarity index 91%
rename from wp-includes/Requests/IRI.php
rename to wp-includes/Requests/src/Iri.php
index 5d80e49572..244578d344 100644
--- a/wp-includes/Requests/IRI.php
+++ b/wp-includes/Requests/src/Iri.php
@@ -2,10 +2,17 @@
 /**
  * IRI parser/serialiser/normaliser
  *
- * @package Requests
- * @subpackage Utilities
+ * @package Requests\Utilities
  */
 
+namespace WpOrg\Requests;
+
+use WpOrg\Requests\Exception;
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Ipv6;
+use WpOrg\Requests\Port;
+use WpOrg\Requests\Utility\InputValidator;
+
 /**
  * IRI parser/serialiser/normaliser
  *
@@ -38,16 +45,15 @@
  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  * POSSIBILITY OF SUCH DAMAGE.
  *
- * @package Requests
- * @subpackage Utilities
+ * @package Requests\Utilities
  * @author Geoffrey Sneddon
  * @author Steve Minutillo
  * @copyright 2007-2009 Geoffrey Sneddon and Steve Minutillo
- * @license http://www.opensource.org/licenses/bsd-license.php
+ * @license https://opensource.org/licenses/bsd-license.php
  * @link http://hg.gsnedders.com/iri/
  *
  * @property string $iri IRI we're working with
- * @property-read string $uri IRI in URI form, {@see to_uri}
+ * @property-read string $uri IRI in URI form, {@see \WpOrg\Requests\Iri::to_uri()}
  * @property string $scheme Scheme part of the IRI
  * @property string $authority Authority part, formatted for a URI (userinfo + host + port)
  * @property string $iauthority Authority part of the IRI (userinfo + host + port)
@@ -63,7 +69,7 @@
  * @property string $fragment Fragment, formatted for a URI (after '#')
  * @property string $ifragment Fragment part of the IRI (after '#')
  */
-class Requests_IRI {
+class Iri {
 	/**
 	 * Scheme
 	 *
@@ -123,19 +129,19 @@ class Requests_IRI {
 	 */
 	protected $normalization = array(
 		'acap' => array(
-			'port' => 674
+			'port' => Port::ACAP,
 		),
 		'dict' => array(
-			'port' => 2628
+			'port' => Port::DICT,
 		),
 		'file' => array(
-			'ihost' => 'localhost'
+			'ihost' => 'localhost',
 		),
 		'http' => array(
-			'port' => 80,
+			'port' => Port::HTTP,
 		),
 		'https' => array(
-			'port' => 443,
+			'port' => Port::HTTPS,
 		),
 	);
 
@@ -240,9 +246,15 @@ class Requests_IRI {
 	/**
 	 * Create a new IRI object, from a specified string
 	 *
-	 * @param string|null $iri
+	 * @param string|Stringable|null $iri
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $iri argument is not a string, Stringable or null.
 	 */
 	public function __construct($iri = null) {
+		if ($iri !== null && InputValidator::is_string_or_stringable($iri) === false) {
+			throw InvalidArgument::create(1, '$iri', 'string|Stringable|null', gettype($iri));
+		}
+
 		$this->set_iri($iri);
 	}
 
@@ -251,13 +263,13 @@ class Requests_IRI {
 	 *
 	 * Returns false if $base is not absolute, otherwise an IRI.
 	 *
-	 * @param Requests_IRI|string $base (Absolute) Base IRI
-	 * @param Requests_IRI|string $relative Relative IRI
-	 * @return Requests_IRI|false
+	 * @param \WpOrg\Requests\Iri|string $base (Absolute) Base IRI
+	 * @param \WpOrg\Requests\Iri|string $relative Relative IRI
+	 * @return \WpOrg\Requests\Iri|false
 	 */
 	public static function absolutize($base, $relative) {
-		if (!($relative instanceof Requests_IRI)) {
-			$relative = new Requests_IRI($relative);
+		if (!($relative instanceof self)) {
+			$relative = new self($relative);
 		}
 		if (!$relative->is_valid()) {
 			return false;
@@ -266,8 +278,8 @@ class Requests_IRI {
 			return clone $relative;
 		}
 
-		if (!($base instanceof Requests_IRI)) {
-			$base = new Requests_IRI($base);
+		if (!($base instanceof self)) {
+			$base = new self($base);
 		}
 		if ($base->scheme === null || !$base->is_valid()) {
 			return false;
@@ -279,7 +291,7 @@ class Requests_IRI {
 				$target->scheme = $base->scheme;
 			}
 			else {
-				$target = new Requests_IRI;
+				$target = new self;
 				$target->scheme = $base->scheme;
 				$target->iuserinfo = $base->iuserinfo;
 				$target->ihost = $base->ihost;
@@ -330,7 +342,7 @@ class Requests_IRI {
 		$iri = trim($iri, "\x20\x09\x0A\x0C\x0D");
 		$has_match = preg_match('/^((?P<scheme>[^:\/?#]+):)?(\/\/(?P<authority>[^\/?#]*))?(?P<path>[^?#]*)(\?(?P<query>[^#]*))?(#(?P<fragment>.*))?$/', $iri, $match);
 		if (!$has_match) {
-			throw new Requests_Exception('Cannot parse supplied IRI', 'iri.cannot_parse', $iri);
+			throw new Exception('Cannot parse supplied IRI', 'iri.cannot_parse', $iri);
 		}
 
 		if ($match[1] === '') {
@@ -413,18 +425,18 @@ class Requests_IRI {
 	/**
 	 * Replace invalid character with percent encoding
 	 *
-	 * @param string $string Input string
+	 * @param string $text Input string
 	 * @param string $extra_chars Valid characters not in iunreserved or
 	 *                            iprivate (this is ASCII-only)
 	 * @param bool $iprivate Allow iprivate
 	 * @return string
 	 */
-	protected function replace_invalid_with_pct_encoding($string, $extra_chars, $iprivate = false) {
+	protected function replace_invalid_with_pct_encoding($text, $extra_chars, $iprivate = false) {
 		// Normalize as many pct-encoded sections as possible
-		$string = preg_replace_callback('/(?:%[A-Fa-f0-9]{2})+/', array($this, 'remove_iunreserved_percent_encoded'), $string);
+		$text = preg_replace_callback('/(?:%[A-Fa-f0-9]{2})+/', array($this, 'remove_iunreserved_percent_encoded'), $text);
 
 		// Replace invalid percent characters
-		$string = preg_replace('/%(?![A-Fa-f0-9]{2})/', '%25', $string);
+		$text = preg_replace('/%(?![A-Fa-f0-9]{2})/', '%25', $text);
 
 		// Add unreserved and % to $extra_chars (the latter is safe because all
 		// pct-encoded sections are now valid).
@@ -432,9 +444,9 @@ class Requests_IRI {
 
 		// Now replace any bytes that aren't allowed with their pct-encoded versions
 		$position = 0;
-		$strlen = strlen($string);
-		while (($position += strspn($string, $extra_chars, $position)) < $strlen) {
-			$value = ord($string[$position]);
+		$strlen = strlen($text);
+		while (($position += strspn($text, $extra_chars, $position)) < $strlen) {
+			$value = ord($text[$position]);
 
 			// Start position
 			$start = $position;
@@ -471,7 +483,7 @@ class Requests_IRI {
 			if ($remaining) {
 				if ($position + $length <= $strlen) {
 					for ($position++; $remaining; $position++) {
-						$value = ord($string[$position]);
+						$value = ord($text[$position]);
 
 						// Check that the byte is valid, then add it to the character:
 						if (($value & 0xC0) === 0x80) {
@@ -522,7 +534,7 @@ class Requests_IRI {
 				}
 
 				for ($j = $start; $j <= $position; $j++) {
-					$string = substr_replace($string, sprintf('%%%02X', ord($string[$j])), $j, 1);
+					$text = substr_replace($text, sprintf('%%%02X', ord($text[$j])), $j, 1);
 					$j += 2;
 					$position += 2;
 					$strlen += 2;
@@ -530,7 +542,7 @@ class Requests_IRI {
 			}
 		}
 
-		return $string;
+		return $text;
 	}
 
 	/**
@@ -539,13 +551,13 @@ class Requests_IRI {
 	 * Removes sequences of percent encoded bytes that represent UTF-8
 	 * encoded characters in iunreserved
 	 *
-	 * @param array $match PCRE match
+	 * @param array $regex_match PCRE match
 	 * @return string Replacement
 	 */
-	protected function remove_iunreserved_percent_encoded($match) {
+	protected function remove_iunreserved_percent_encoded($regex_match) {
 		// As we just have valid percent encoded sequences we can just explode
 		// and ignore the first member of the returned array (an empty string).
-		$bytes = explode('%', $match[0]);
+		$bytes = explode('%', $regex_match[0]);
 
 		// Initialize the new string (this is what will be returned) and that
 		// there are no bytes remaining in the current sequence (unsurprising
@@ -721,6 +733,9 @@ class Requests_IRI {
 		if ($iri === null) {
 			return true;
 		}
+
+		$iri = (string) $iri;
+
 		if (isset($cache[$iri])) {
 			list($this->scheme,
 				 $this->iuserinfo,
@@ -733,7 +748,7 @@ class Requests_IRI {
 			return $return;
 		}
 
-		$parsed = $this->parse_iri((string) $iri);
+		$parsed = $this->parse_iri($iri);
 
 		$return = $this->set_scheme($parsed['scheme'])
 			&& $this->set_authority($parsed['authority'])
@@ -863,8 +878,8 @@ class Requests_IRI {
 			return true;
 		}
 		if (substr($ihost, 0, 1) === '[' && substr($ihost, -1) === ']') {
-			if (Requests_IPv6::check_ipv6(substr($ihost, 1, -1))) {
-				$this->ihost = '[' . Requests_IPv6::compress(substr($ihost, 1, -1)) . ']';
+			if (Ipv6::check_ipv6(substr($ihost, 1, -1))) {
+				$this->ihost = '[' . Ipv6::compress(substr($ihost, 1, -1)) . ']';
 			}
 			else {
 				$this->ihost = null;
@@ -985,11 +1000,11 @@ class Requests_IRI {
 	/**
 	 * Convert an IRI to a URI (or parts thereof)
 	 *
-	 * @param string|bool IRI to convert (or false from {@see get_iri})
+	 * @param string|bool $iri IRI to convert (or false from {@see \WpOrg\Requests\Iri::get_iri()})
 	 * @return string|false URI if IRI is valid, false otherwise.
 	 */
-	protected function to_uri($string) {
-		if (!is_string($string)) {
+	protected function to_uri($iri) {
+		if (!is_string($iri)) {
 			return false;
 		}
 
@@ -999,14 +1014,14 @@ class Requests_IRI {
 		}
 
 		$position = 0;
-		$strlen = strlen($string);
-		while (($position += strcspn($string, $non_ascii, $position)) < $strlen) {
-			$string = substr_replace($string, sprintf('%%%02X', ord($string[$position])), $position, 1);
+		$strlen = strlen($iri);
+		while (($position += strcspn($iri, $non_ascii, $position)) < $strlen) {
+			$iri = substr_replace($iri, sprintf('%%%02X', ord($iri[$position])), $position, 1);
 			$position += 3;
 			$strlen += 2;
 		}
 
-		return $string;
+		return $iri;
 	}
 
 	/**
diff --git a/wp-includes/Requests/src/Port.php b/wp-includes/Requests/src/Port.php
new file mode 100644
index 0000000000..5545409385
--- /dev/null
+++ b/wp-includes/Requests/src/Port.php
@@ -0,0 +1,75 @@
+<?php
+/**
+ * Port utilities for Requests
+ *
+ * @package Requests\Utilities
+ * @since   2.0.0
+ */
+
+namespace WpOrg\Requests;
+
+use WpOrg\Requests\Exception;
+use WpOrg\Requests\Exception\InvalidArgument;
+
+/**
+ * Find the correct port depending on the Request type.
+ *
+ * @package Requests\Utilities
+ * @since   2.0.0
+ */
+final class Port {
+
+	/**
+	 * Port to use with Acap requests.
+	 *
+	 * @var int
+	 */
+	const ACAP = 674;
+
+	/**
+	 * Port to use with Dictionary requests.
+	 *
+	 * @var int
+	 */
+	const DICT = 2628;
+
+	/**
+	 * Port to use with HTTP requests.
+	 *
+	 * @var int
+	 */
+	const HTTP = 80;
+
+	/**
+	 * Port to use with HTTP over SSL requests.
+	 *
+	 * @var int
+	 */
+	const HTTPS = 443;
+
+	/**
+	 * Retrieve the port number to use.
+	 *
+	 * @param string $type Request type.
+	 *                     The following requests types are supported:
+	 *                     'acap', 'dict', 'http' and 'https'.
+	 *
+	 * @return int
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When a non-string input has been passed.
+	 * @throws \WpOrg\Requests\Exception                 When a non-supported port is requested ('portnotsupported').
+	 */
+	public static function get($type) {
+		if (!is_string($type)) {
+			throw InvalidArgument::create(1, '$type', 'string', gettype($type));
+		}
+
+		$type = strtoupper($type);
+		if (!defined("self::{$type}")) {
+			$message = sprintf('Invalid port type (%s) passed', $type);
+			throw new Exception($message, 'portnotsupported');
+		}
+
+		return constant("self::{$type}");
+	}
+}
diff --git a/wp-includes/Requests/src/Proxy.php b/wp-includes/Requests/src/Proxy.php
new file mode 100644
index 0000000000..18797a27f8
--- /dev/null
+++ b/wp-includes/Requests/src/Proxy.php
@@ -0,0 +1,38 @@
+<?php
+/**
+ * Proxy connection interface
+ *
+ * @package Requests\Proxy
+ * @since   1.6
+ */
+
+namespace WpOrg\Requests;
+
+use WpOrg\Requests\Hooks;
+
+/**
+ * Proxy connection interface
+ *
+ * Implement this interface to handle proxy settings and authentication
+ *
+ * Parameters should be passed via the constructor where possible, as this
+ * makes it much easier for users to use your provider.
+ *
+ * @see \WpOrg\Requests\Hooks
+ *
+ * @package Requests\Proxy
+ * @since   1.6
+ */
+interface Proxy {
+	/**
+	 * Register hooks as needed
+	 *
+	 * This method is called in {@see \WpOrg\Requests\Requests::request()} when the user
+	 * has set an instance as the 'auth' option. Use this callback to register all the
+	 * hooks you'll need.
+	 *
+	 * @see \WpOrg\Requests\Hooks::register()
+	 * @param \WpOrg\Requests\Hooks $hooks Hook system
+	 */
+	public function register(Hooks $hooks);
+}
diff --git a/wp-includes/Requests/Proxy/HTTP.php b/wp-includes/Requests/src/Proxy/Http.php
similarity index 56%
rename from wp-includes/Requests/Proxy/HTTP.php
rename to wp-includes/Requests/src/Proxy/Http.php
index 25bb95a94a..e553c9c508 100644
--- a/wp-includes/Requests/Proxy/HTTP.php
+++ b/wp-includes/Requests/src/Proxy/Http.php
@@ -2,21 +2,26 @@
 /**
  * HTTP Proxy connection interface
  *
- * @package Requests
- * @subpackage Proxy
- * @since 1.6
+ * @package Requests\Proxy
+ * @since   1.6
  */
 
+namespace WpOrg\Requests\Proxy;
+
+use WpOrg\Requests\Exception\ArgumentCount;
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Hooks;
+use WpOrg\Requests\Proxy;
+
 /**
  * HTTP Proxy connection interface
  *
  * Provides a handler for connection via an HTTP proxy
  *
- * @package Requests
- * @subpackage Proxy
- * @since 1.6
+ * @package Requests\Proxy
+ * @since   1.6
  */
-class Requests_Proxy_HTTP implements Requests_Proxy {
+final class Http implements Proxy {
 	/**
 	 * Proxy host and port
 	 *
@@ -51,24 +56,32 @@ class Requests_Proxy_HTTP implements Requests_Proxy {
 	 * Constructor
 	 *
 	 * @since 1.6
-	 * @throws Requests_Exception On incorrect number of arguments (`authbasicbadargs`)
-	 * @param array|null $args Array of user and password. Must have exactly two elements
+	 *
+	 * @param array|string|null $args Proxy as a string or an array of proxy, user and password.
+	 *                                When passed as an array, must have exactly one (proxy)
+	 *                                or three elements (proxy, user, password).
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not an array, a string or null.
+	 * @throws \WpOrg\Requests\Exception\ArgumentCount On incorrect number of arguments (`proxyhttpbadargs`)
 	 */
 	public function __construct($args = null) {
 		if (is_string($args)) {
 			$this->proxy = $args;
-		}
-		elseif (is_array($args)) {
+		} elseif (is_array($args)) {
 			if (count($args) === 1) {
 				list($this->proxy) = $args;
-			}
-			elseif (count($args) === 3) {
+			} elseif (count($args) === 3) {
 				list($this->proxy, $this->user, $this->pass) = $args;
 				$this->use_authentication                    = true;
+			} else {
+				throw ArgumentCount::create(
+					'an array with exactly one element or exactly three elements',
+					count($args),
+					'proxyhttpbadargs'
+				);
 			}
-			else {
-				throw new Requests_Exception('Invalid number of arguments', 'proxyhttpbadargs');
-			}
+		} elseif ($args !== null) {
+			throw InvalidArgument::create(1, '$args', 'array|string|null', gettype($args));
 		}
 	}
 
@@ -76,19 +89,19 @@ class Requests_Proxy_HTTP implements Requests_Proxy {
 	 * Register the necessary callbacks
 	 *
 	 * @since 1.6
-	 * @see curl_before_send
-	 * @see fsockopen_remote_socket
-	 * @see fsockopen_remote_host_path
-	 * @see fsockopen_header
-	 * @param Requests_Hooks $hooks Hook system
+	 * @see \WpOrg\Requests\Proxy\Http::curl_before_send()
+	 * @see \WpOrg\Requests\Proxy\Http::fsockopen_remote_socket()
+	 * @see \WpOrg\Requests\Proxy\Http::fsockopen_remote_host_path()
+	 * @see \WpOrg\Requests\Proxy\Http::fsockopen_header()
+	 * @param \WpOrg\Requests\Hooks $hooks Hook system
 	 */
-	public function register(Requests_Hooks $hooks) {
-		$hooks->register('curl.before_send', array($this, 'curl_before_send'));
+	public function register(Hooks $hooks) {
+		$hooks->register('curl.before_send', [$this, 'curl_before_send']);
 
-		$hooks->register('fsockopen.remote_socket', array($this, 'fsockopen_remote_socket'));
-		$hooks->register('fsockopen.remote_host_path', array($this, 'fsockopen_remote_host_path'));
+		$hooks->register('fsockopen.remote_socket', [$this, 'fsockopen_remote_socket']);
+		$hooks->register('fsockopen.remote_host_path', [$this, 'fsockopen_remote_host_path']);
 		if ($this->use_authentication) {
-			$hooks->register('fsockopen.after_headers', array($this, 'fsockopen_header'));
+			$hooks->register('fsockopen.after_headers', [$this, 'fsockopen_header']);
 		}
 	}
 
@@ -96,7 +109,7 @@ class Requests_Proxy_HTTP implements Requests_Proxy {
 	 * Set cURL parameters before the data is sent
 	 *
 	 * @since 1.6
-	 * @param resource $handle cURL resource
+	 * @param resource|\CurlHandle $handle cURL handle
 	 */
 	public function curl_before_send(&$handle) {
 		curl_setopt($handle, CURLOPT_PROXYTYPE, CURLPROXY_HTTP);
diff --git a/wp-includes/Requests/src/Requests.php b/wp-includes/Requests/src/Requests.php
new file mode 100644
index 0000000000..a8d9d7e539
--- /dev/null
+++ b/wp-includes/Requests/src/Requests.php
@@ -0,0 +1,1095 @@
+<?php
+/**
+ * Requests for PHP
+ *
+ * Inspired by Requests for Python.
+ *
+ * Based on concepts from SimplePie_File, RequestCore and WP_Http.
+ *
+ * @package Requests
+ */
+
+namespace WpOrg\Requests;
+
+use WpOrg\Requests\Auth\Basic;
+use WpOrg\Requests\Capability;
+use WpOrg\Requests\Cookie\Jar;
+use WpOrg\Requests\Exception;
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Hooks;
+use WpOrg\Requests\IdnaEncoder;
+use WpOrg\Requests\Iri;
+use WpOrg\Requests\Proxy\Http;
+use WpOrg\Requests\Response;
+use WpOrg\Requests\Transport\Curl;
+use WpOrg\Requests\Transport\Fsockopen;
+use WpOrg\Requests\Utility\InputValidator;
+
+/**
+ * Requests for PHP
+ *
+ * Inspired by Requests for Python.
+ *
+ * Based on concepts from SimplePie_File, RequestCore and WP_Http.
+ *
+ * @package Requests
+ */
+class Requests {
+	/**
+	 * POST method
+	 *
+	 * @var string
+	 */
+	const POST = 'POST';
+
+	/**
+	 * PUT method
+	 *
+	 * @var string
+	 */
+	const PUT = 'PUT';
+
+	/**
+	 * GET method
+	 *
+	 * @var string
+	 */
+	const GET = 'GET';
+
+	/**
+	 * HEAD method
+	 *
+	 * @var string
+	 */
+	const HEAD = 'HEAD';
+
+	/**
+	 * DELETE method
+	 *
+	 * @var string
+	 */
+	const DELETE = 'DELETE';
+
+	/**
+	 * OPTIONS method
+	 *
+	 * @var string
+	 */
+	const OPTIONS = 'OPTIONS';
+
+	/**
+	 * TRACE method
+	 *
+	 * @var string
+	 */
+	const TRACE = 'TRACE';
+
+	/**
+	 * PATCH method
+	 *
+	 * @link https://tools.ietf.org/html/rfc5789
+	 * @var string
+	 */
+	const PATCH = 'PATCH';
+
+	/**
+	 * Default size of buffer size to read streams
+	 *
+	 * @var integer
+	 */
+	const BUFFER_SIZE = 1160;
+
+	/**
+	 * Option defaults.
+	 *
+	 * @see \WpOrg\Requests\Requests::get_default_options()
+	 * @see \WpOrg\Requests\Requests::request() for values returned by this method
+	 *
+	 * @since 2.0.0
+	 *
+	 * @var array
+	 */
+	const OPTION_DEFAULTS = [
+		'timeout'          => 10,
+		'connect_timeout'  => 10,
+		'useragent'        => 'php-requests/' . self::VERSION,
+		'protocol_version' => 1.1,
+		'redirected'       => 0,
+		'redirects'        => 10,
+		'follow_redirects' => true,
+		'blocking'         => true,
+		'type'             => self::GET,
+		'filename'         => false,
+		'auth'             => false,
+		'proxy'            => false,
+		'cookies'          => false,
+		'max_bytes'        => false,
+		'idn'              => true,
+		'hooks'            => null,
+		'transport'        => null,
+		'verify'           => null,
+		'verifyname'       => true,
+	];
+
+	/**
+	 * Default supported Transport classes.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @var array
+	 */
+	const DEFAULT_TRANSPORTS = [
+		Curl::class      => Curl::class,
+		Fsockopen::class => Fsockopen::class,
+	];
+
+	/**
+	 * Current version of Requests
+	 *
+	 * @var string
+	 */
+	const VERSION = '2.0.5';
+
+	/**
+	 * Selected transport name
+	 *
+	 * Use {@see \WpOrg\Requests\Requests::get_transport()} instead
+	 *
+	 * @var array
+	 */
+	public static $transport = [];
+
+	/**
+	 * Registered transport classes
+	 *
+	 * @var array
+	 */
+	protected static $transports = [];
+
+	/**
+	 * Default certificate path.
+	 *
+	 * @see \WpOrg\Requests\Requests::get_certificate_path()
+	 * @see \WpOrg\Requests\Requests::set_certificate_path()
+	 *
+	 * @var string
+	 */
+	protected static $certificate_path = __DIR__ . '/../certificates/cacert.pem';
+
+	/**
+	 * All (known) valid deflate, gzip header magic markers.
+	 *
+	 * These markers relate to different compression levels.
+	 *
+	 * @link https://stackoverflow.com/a/43170354/482864 Marker source.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @var array
+	 */
+	private static $magic_compression_headers = [
+		"\x1f\x8b" => true, // Gzip marker.
+		"\x78\x01" => true, // Zlib marker - level 1.
+		"\x78\x5e" => true, // Zlib marker - level 2 to 5.
+		"\x78\x9c" => true, // Zlib marker - level 6.
+		"\x78\xda" => true, // Zlib marker - level 7 to 9.
+	];
+
+	/**
+	 * This is a static class, do not instantiate it
+	 *
+	 * @codeCoverageIgnore
+	 */
+	private function __construct() {}
+
+	/**
+	 * Register a transport
+	 *
+	 * @param string $transport Transport class to add, must support the \WpOrg\Requests\Transport interface
+	 */
+	public static function add_transport($transport) {
+		if (empty(self::$transports)) {
+			self::$transports = self::DEFAULT_TRANSPORTS;
+		}
+
+		self::$transports[$transport] = $transport;
+	}
+
+	/**
+	 * Get the fully qualified class name (FQCN) for a working transport.
+	 *
+	 * @param array<string, bool> $capabilities Optional. Associative array of capabilities to test against, i.e. `['<capability>' => true]`.
+	 * @return string FQCN of the transport to use, or an empty string if no transport was
+	 *                found which provided the requested capabilities.
+	 */
+	protected static function get_transport_class(array $capabilities = []) {
+		// Caching code, don't bother testing coverage.
+		// @codeCoverageIgnoreStart
+		// Array of capabilities as a string to be used as an array key.
+		ksort($capabilities);
+		$cap_string = serialize($capabilities);
+
+		// Don't search for a transport if it's already been done for these $capabilities.
+		if (isset(self::$transport[$cap_string])) {
+			return self::$transport[$cap_string];
+		}
+
+		// Ensure we will not run this same check again later on.
+		self::$transport[$cap_string] = '';
+		// @codeCoverageIgnoreEnd
+
+		if (empty(self::$transports)) {
+			self::$transports = self::DEFAULT_TRANSPORTS;
+		}
+
+		// Find us a working transport.
+		foreach (self::$transports as $class) {
+			if (!class_exists($class)) {
+				continue;
+			}
+
+			$result = $class::test($capabilities);
+			if ($result === true) {
+				self::$transport[$cap_string] = $class;
+				break;
+			}
+		}
+
+		return self::$transport[$cap_string];
+	}
+
+	/**
+	 * Get a working transport.
+	 *
+	 * @param array<string, bool> $capabilities Optional. Associative array of capabilities to test against, i.e. `['<capability>' => true]`.
+	 * @return \WpOrg\Requests\Transport
+	 * @throws \WpOrg\Requests\Exception If no valid transport is found (`notransport`).
+	 */
+	protected static function get_transport(array $capabilities = []) {
+		$class = self::get_transport_class($capabilities);
+
+		if ($class === '') {
+			throw new Exception('No working transports found', 'notransport', self::$transports);
+		}
+
+		return new $class();
+	}
+
+	/**
+	 * Checks to see if we have a transport for the capabilities requested.
+	 *
+	 * Supported capabilities can be found in the {@see \WpOrg\Requests\Capability}
+	 * interface as constants.
+	 *
+	 * Example usage:
+	 * `Requests::has_capabilities([Capability::SSL => true])`.
+	 *
+	 * @param array<string, bool> $capabilities Optional. Associative array of capabilities to test against, i.e. `['<capability>' => true]`.
+	 * @return bool Whether the transport has the requested capabilities.
+	 */
+	public static function has_capabilities(array $capabilities = []) {
+		return self::get_transport_class($capabilities) !== '';
+	}
+
+	/**#@+
+	 * @see \WpOrg\Requests\Requests::request()
+	 * @param string $url
+	 * @param array $headers
+	 * @param array $options
+	 * @return \WpOrg\Requests\Response
+	 */
+	/**
+	 * Send a GET request
+	 */
+	public static function get($url, $headers = [], $options = []) {
+		return self::request($url, $headers, null, self::GET, $options);
+	}
+
+	/**
+	 * Send a HEAD request
+	 */
+	public static function head($url, $headers = [], $options = []) {
+		return self::request($url, $headers, null, self::HEAD, $options);
+	}
+
+	/**
+	 * Send a DELETE request
+	 */
+	public static function delete($url, $headers = [], $options = []) {
+		return self::request($url, $headers, null, self::DELETE, $options);
+	}
+
+	/**
+	 * Send a TRACE request
+	 */
+	public static function trace($url, $headers = [], $options = []) {
+		return self::request($url, $headers, null, self::TRACE, $options);
+	}
+	/**#@-*/
+
+	/**#@+
+	 * @see \WpOrg\Requests\Requests::request()
+	 * @param string $url
+	 * @param array $headers
+	 * @param array $data
+	 * @param array $options
+	 * @return \WpOrg\Requests\Response
+	 */
+	/**
+	 * Send a POST request
+	 */
+	public static function post($url, $headers = [], $data = [], $options = []) {
+		return self::request($url, $headers, $data, self::POST, $options);
+	}
+	/**
+	 * Send a PUT request
+	 */
+	public static function put($url, $headers = [], $data = [], $options = []) {
+		return self::request($url, $headers, $data, self::PUT, $options);
+	}
+
+	/**
+	 * Send an OPTIONS request
+	 */
+	public static function options($url, $headers = [], $data = [], $options = []) {
+		return self::request($url, $headers, $data, self::OPTIONS, $options);
+	}
+
+	/**
+	 * Send a PATCH request
+	 *
+	 * Note: Unlike {@see \WpOrg\Requests\Requests::post()} and {@see \WpOrg\Requests\Requests::put()},
+	 * `$headers` is required, as the specification recommends that should send an ETag
+	 *
+	 * @link https://tools.ietf.org/html/rfc5789
+	 */
+	public static function patch($url, $headers, $data = [], $options = []) {
+		return self::request($url, $headers, $data, self::PATCH, $options);
+	}
+	/**#@-*/
+
+	/**
+	 * Main interface for HTTP requests
+	 *
+	 * This method initiates a request and sends it via a transport before
+	 * parsing.
+	 *
+	 * The `$options` parameter takes an associative array with the following
+	 * options:
+	 *
+	 * - `timeout`: How long should we wait for a response?
+	 *    Note: for cURL, a minimum of 1 second applies, as DNS resolution
+	 *    operates at second-resolution only.
+	 *    (float, seconds with a millisecond precision, default: 10, example: 0.01)
+	 * - `connect_timeout`: How long should we wait while trying to connect?
+	 *    (float, seconds with a millisecond precision, default: 10, example: 0.01)
+	 * - `useragent`: Useragent to send to the server
+	 *    (string, default: php-requests/$version)
+	 * - `follow_redirects`: Should we follow 3xx redirects?
+	 *    (boolean, default: true)
+	 * - `redirects`: How many times should we redirect before erroring?
+	 *    (integer, default: 10)
+	 * - `blocking`: Should we block processing on this request?
+	 *    (boolean, default: true)
+	 * - `filename`: File to stream the body to instead.
+	 *    (string|boolean, default: false)
+	 * - `auth`: Authentication handler or array of user/password details to use
+	 *    for Basic authentication
+	 *    (\WpOrg\Requests\Auth|array|boolean, default: false)
+	 * - `proxy`: Proxy details to use for proxy by-passing and authentication
+	 *    (\WpOrg\Requests\Proxy|array|string|boolean, default: false)
+	 * - `max_bytes`: Limit for the response body size.
+	 *    (integer|boolean, default: false)
+	 * - `idn`: Enable IDN parsing
+	 *    (boolean, default: true)
+	 * - `transport`: Custom transport. Either a class name, or a
+	 *    transport object. Defaults to the first working transport from
+	 *    {@see \WpOrg\Requests\Requests::getTransport()}
+	 *    (string|\WpOrg\Requests\Transport, default: {@see \WpOrg\Requests\Requests::getTransport()})
+	 * - `hooks`: Hooks handler.
+	 *    (\WpOrg\Requests\HookManager, default: new WpOrg\Requests\Hooks())
+	 * - `verify`: Should we verify SSL certificates? Allows passing in a custom
+	 *    certificate file as a string. (Using true uses the system-wide root
+	 *    certificate store instead, but this may have different behaviour
+	 *    across transports.)
+	 *    (string|boolean, default: certificates/cacert.pem)
+	 * - `verifyname`: Should we verify the common name in the SSL certificate?
+	 *    (boolean, default: true)
+	 * - `data_format`: How should we send the `$data` parameter?
+	 *    (string, one of 'query' or 'body', default: 'query' for
+	 *    HEAD/GET/DELETE, 'body' for POST/PUT/OPTIONS/PATCH)
+	 *
+	 * @param string|Stringable $url URL to request
+	 * @param array $headers Extra headers to send with the request
+	 * @param array|null $data Data to send either as a query string for GET/HEAD requests, or in the body for POST requests
+	 * @param string $type HTTP request type (use Requests constants)
+	 * @param array $options Options for the request (see description for more information)
+	 * @return \WpOrg\Requests\Response
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $url argument is not a string or Stringable.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $type argument is not a string.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $options argument is not an array.
+	 * @throws \WpOrg\Requests\Exception On invalid URLs (`nonhttp`)
+	 */
+	public static function request($url, $headers = [], $data = [], $type = self::GET, $options = []) {
+		if (InputValidator::is_string_or_stringable($url) === false) {
+			throw InvalidArgument::create(1, '$url', 'string|Stringable', gettype($url));
+		}
+
+		if (is_string($type) === false) {
+			throw InvalidArgument::create(4, '$type', 'string', gettype($type));
+		}
+
+		if (is_array($options) === false) {
+			throw InvalidArgument::create(5, '$options', 'array', gettype($options));
+		}
+
+		if (empty($options['type'])) {
+			$options['type'] = $type;
+		}
+
+		$options = array_merge(self::get_default_options(), $options);
+
+		self::set_defaults($url, $headers, $data, $type, $options);
+
+		$options['hooks']->dispatch('requests.before_request', [&$url, &$headers, &$data, &$type, &$options]);
+
+		if (!empty($options['transport'])) {
+			$transport = $options['transport'];
+
+			if (is_string($options['transport'])) {
+				$transport = new $transport();
+			}
+		} else {
+			$need_ssl     = (stripos($url, 'https://') === 0);
+			$capabilities = [Capability::SSL => $need_ssl];
+			$transport    = self::get_transport($capabilities);
+		}
+
+		$response = $transport->request($url, $headers, $data, $options);
+
+		$options['hooks']->dispatch('requests.before_parse', [&$response, $url, $headers, $data, $type, $options]);
+
+		return self::parse_response($response, $url, $headers, $data, $options);
+	}
+
+	/**
+	 * Send multiple HTTP requests simultaneously
+	 *
+	 * The `$requests` parameter takes an associative or indexed array of
+	 * request fields. The key of each request can be used to match up the
+	 * request with the returned data, or with the request passed into your
+	 * `multiple.request.complete` callback.
+	 *
+	 * The request fields value is an associative array with the following keys:
+	 *
+	 * - `url`: Request URL Same as the `$url` parameter to
+	 *    {@see \WpOrg\Requests\Requests::request()}
+	 *    (string, required)
+	 * - `headers`: Associative array of header fields. Same as the `$headers`
+	 *    parameter to {@see \WpOrg\Requests\Requests::request()}
+	 *    (array, default: `array()`)
+	 * - `data`: Associative array of data fields or a string. Same as the
+	 *    `$data` parameter to {@see \WpOrg\Requests\Requests::request()}
+	 *    (array|string, default: `array()`)
+	 * - `type`: HTTP request type (use \WpOrg\Requests\Requests constants). Same as the `$type`
+	 *    parameter to {@see \WpOrg\Requests\Requests::request()}
+	 *    (string, default: `\WpOrg\Requests\Requests::GET`)
+	 * - `cookies`: Associative array of cookie name to value, or cookie jar.
+	 *    (array|\WpOrg\Requests\Cookie\Jar)
+	 *
+	 * If the `$options` parameter is specified, individual requests will
+	 * inherit options from it. This can be used to use a single hooking system,
+	 * or set all the types to `\WpOrg\Requests\Requests::POST`, for example.
+	 *
+	 * In addition, the `$options` parameter takes the following global options:
+	 *
+	 * - `complete`: A callback for when a request is complete. Takes two
+	 *    parameters, a \WpOrg\Requests\Response/\WpOrg\Requests\Exception reference, and the
+	 *    ID from the request array (Note: this can also be overridden on a
+	 *    per-request basis, although that's a little silly)
+	 *    (callback)
+	 *
+	 * @param array $requests Requests data (see description for more information)
+	 * @param array $options Global and default options (see {@see \WpOrg\Requests\Requests::request()})
+	 * @return array Responses (either \WpOrg\Requests\Response or a \WpOrg\Requests\Exception object)
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $requests argument is not an array or iterable object with array access.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $options argument is not an array.
+	 */
+	public static function request_multiple($requests, $options = []) {
+		if (InputValidator::has_array_access($requests) === false || InputValidator::is_iterable($requests) === false) {
+			throw InvalidArgument::create(1, '$requests', 'array|ArrayAccess&Traversable', gettype($requests));
+		}
+
+		if (is_array($options) === false) {
+			throw InvalidArgument::create(2, '$options', 'array', gettype($options));
+		}
+
+		$options = array_merge(self::get_default_options(true), $options);
+
+		if (!empty($options['hooks'])) {
+			$options['hooks']->register('transport.internal.parse_response', [static::class, 'parse_multiple']);
+			if (!empty($options['complete'])) {
+				$options['hooks']->register('multiple.request.complete', $options['complete']);
+			}
+		}
+
+		foreach ($requests as $id => &$request) {
+			if (!isset($request['headers'])) {
+				$request['headers'] = [];
+			}
+
+			if (!isset($request['data'])) {
+				$request['data'] = [];
+			}
+
+			if (!isset($request['type'])) {
+				$request['type'] = self::GET;
+			}
+
+			if (!isset($request['options'])) {
+				$request['options']         = $options;
+				$request['options']['type'] = $request['type'];
+			} else {
+				if (empty($request['options']['type'])) {
+					$request['options']['type'] = $request['type'];
+				}
+
+				$request['options'] = array_merge($options, $request['options']);
+			}
+
+			self::set_defaults($request['url'], $request['headers'], $request['data'], $request['type'], $request['options']);
+
+			// Ensure we only hook in once
+			if ($request['options']['hooks'] !== $options['hooks']) {
+				$request['options']['hooks']->register('transport.internal.parse_response', [static::class, 'parse_multiple']);
+				if (!empty($request['options']['complete'])) {
+					$request['options']['hooks']->register('multiple.request.complete', $request['options']['complete']);
+				}
+			}
+		}
+
+		unset($request);
+
+		if (!empty($options['transport'])) {
+			$transport = $options['transport'];
+
+			if (is_string($options['transport'])) {
+				$transport = new $transport();
+			}
+		} else {
+			$transport = self::get_transport();
+		}
+
+		$responses = $transport->request_multiple($requests, $options);
+
+		foreach ($responses as $id => &$response) {
+			// If our hook got messed with somehow, ensure we end up with the
+			// correct response
+			if (is_string($response)) {
+				$request = $requests[$id];
+				self::parse_multiple($response, $request);
+				$request['options']['hooks']->dispatch('multiple.request.complete', [&$response, $id]);
+			}
+		}
+
+		return $responses;
+	}
+
+	/**
+	 * Get the default options
+	 *
+	 * @see \WpOrg\Requests\Requests::request() for values returned by this method
+	 * @param boolean $multirequest Is this a multirequest?
+	 * @return array Default option values
+	 */
+	protected static function get_default_options($multirequest = false) {
+		$defaults           = static::OPTION_DEFAULTS;
+		$defaults['verify'] = self::$certificate_path;
+
+		if ($multirequest !== false) {
+			$defaults['complete'] = null;
+		}
+
+		return $defaults;
+	}
+
+	/**
+	 * Get default certificate path.
+	 *
+	 * @return string Default certificate path.
+	 */
+	public static function get_certificate_path() {
+		return self::$certificate_path;
+	}
+
+	/**
+	 * Set default certificate path.
+	 *
+	 * @param string|Stringable|bool $path Certificate path, pointing to a PEM file.
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $url argument is not a string, Stringable or boolean.
+	 */
+	public static function set_certificate_path($path) {
+		if (InputValidator::is_string_or_stringable($path) === false && is_bool($path) === false) {
+			throw InvalidArgument::create(1, '$path', 'string|Stringable|bool', gettype($path));
+		}
+
+		self::$certificate_path = $path;
+	}
+
+	/**
+	 * Set the default values
+	 *
+	 * @param string $url URL to request
+	 * @param array $headers Extra headers to send with the request
+	 * @param array|null $data Data to send either as a query string for GET/HEAD requests, or in the body for POST requests
+	 * @param string $type HTTP request type
+	 * @param array $options Options for the request
+	 * @return void $options is updated with the results
+	 *
+	 * @throws \WpOrg\Requests\Exception When the $url is not an http(s) URL.
+	 */
+	protected static function set_defaults(&$url, &$headers, &$data, &$type, &$options) {
+		if (!preg_match('/^http(s)?:\/\//i', $url, $matches)) {
+			throw new Exception('Only HTTP(S) requests are handled.', 'nonhttp', $url);
+		}
+
+		if (empty($options['hooks'])) {
+			$options['hooks'] = new Hooks();
+		}
+
+		if (is_array($options['auth'])) {
+			$options['auth'] = new Basic($options['auth']);
+		}
+
+		if ($options['auth'] !== false) {
+			$options['auth']->register($options['hooks']);
+		}
+
+		if (is_string($options['proxy']) || is_array($options['proxy'])) {
+			$options['proxy'] = new Http($options['proxy']);
+		}
+
+		if ($options['proxy'] !== false) {
+			$options['proxy']->register($options['hooks']);
+		}
+
+		if (is_array($options['cookies'])) {
+			$options['cookies'] = new Jar($options['cookies']);
+		} elseif (empty($options['cookies'])) {
+			$options['cookies'] = new Jar();
+		}
+
+		if ($options['cookies'] !== false) {
+			$options['cookies']->register($options['hooks']);
+		}
+
+		if ($options['idn'] !== false) {
+			$iri       = new Iri($url);
+			$iri->host = IdnaEncoder::encode($iri->ihost);
+			$url       = $iri->uri;
+		}
+
+		// Massage the type to ensure we support it.
+		$type = strtoupper($type);
+
+		if (!isset($options['data_format'])) {
+			if (in_array($type, [self::HEAD, self::GET, self::DELETE], true)) {
+				$options['data_format'] = 'query';
+			} else {
+				$options['data_format'] = 'body';
+			}
+		}
+	}
+
+	/**
+	 * HTTP response parser
+	 *
+	 * @param string $headers Full response text including headers and body
+	 * @param string $url Original request URL
+	 * @param array $req_headers Original $headers array passed to {@link request()}, in case we need to follow redirects
+	 * @param array $req_data Original $data array passed to {@link request()}, in case we need to follow redirects
+	 * @param array $options Original $options array passed to {@link request()}, in case we need to follow redirects
+	 * @return \WpOrg\Requests\Response
+	 *
+	 * @throws \WpOrg\Requests\Exception On missing head/body separator (`requests.no_crlf_separator`)
+	 * @throws \WpOrg\Requests\Exception On missing head/body separator (`noversion`)
+	 * @throws \WpOrg\Requests\Exception On missing head/body separator (`toomanyredirects`)
+	 */
+	protected static function parse_response($headers, $url, $req_headers, $req_data, $options) {
+		$return = new Response();
+		if (!$options['blocking']) {
+			return $return;
+		}
+
+		$return->raw  = $headers;
+		$return->url  = (string) $url;
+		$return->body = '';
+
+		if (!$options['filename']) {
+			$pos = strpos($headers, "\r\n\r\n");
+			if ($pos === false) {
+				// Crap!
+				throw new Exception('Missing header/body separator', 'requests.no_crlf_separator');
+			}
+
+			$headers = substr($return->raw, 0, $pos);
+			// Headers will always be separated from the body by two new lines - `\n\r\n\r`.
+			$body = substr($return->raw, $pos + 4);
+			if (!empty($body)) {
+				$return->body = $body;
+			}
+		}
+
+		// Pretend CRLF = LF for compatibility (RFC 2616, section 19.3)
+		$headers = str_replace("\r\n", "\n", $headers);
+		// Unfold headers (replace [CRLF] 1*( SP | HT ) with SP) as per RFC 2616 (section 2.2)
+		$headers = preg_replace('/\n[ \t]/', ' ', $headers);
+		$headers = explode("\n", $headers);
+		preg_match('#^HTTP/(1\.\d)[ \t]+(\d+)#i', array_shift($headers), $matches);
+		if (empty($matches)) {
+			throw new Exception('Response could not be parsed', 'noversion', $headers);
+		}
+
+		$return->protocol_version = (float) $matches[1];
+		$return->status_code      = (int) $matches[2];
+		if ($return->status_code >= 200 && $return->status_code < 300) {
+			$return->success = true;
+		}
+
+		foreach ($headers as $header) {
+			list($key, $value) = explode(':', $header, 2);
+			$value             = trim($value);
+			preg_replace('#(\s+)#i', ' ', $value);
+			$return->headers[$key] = $value;
+		}
+
+		if (isset($return->headers['transfer-encoding'])) {
+			$return->body = self::decode_chunked($return->body);
+			unset($return->headers['transfer-encoding']);
+		}
+
+		if (isset($return->headers['content-encoding'])) {
+			$return->body = self::decompress($return->body);
+		}
+
+		//fsockopen and cURL compatibility
+		if (isset($return->headers['connection'])) {
+			unset($return->headers['connection']);
+		}
+
+		$options['hooks']->dispatch('requests.before_redirect_check', [&$return, $req_headers, $req_data, $options]);
+
+		if ($return->is_redirect() && $options['follow_redirects'] === true) {
+			if (isset($return->headers['location']) && $options['redirected'] < $options['redirects']) {
+				if ($return->status_code === 303) {
+					$options['type'] = self::GET;
+				}
+
+				$options['redirected']++;
+				$location = $return->headers['location'];
+				if (strpos($location, 'http://') !== 0 && strpos($location, 'https://') !== 0) {
+					// relative redirect, for compatibility make it absolute
+					$location = Iri::absolutize($url, $location);
+					$location = $location->uri;
+				}
+
+				$hook_args = [
+					&$location,
+					&$req_headers,
+					&$req_data,
+					&$options,
+					$return,
+				];
+				$options['hooks']->dispatch('requests.before_redirect', $hook_args);
+				$redirected            = self::request($location, $req_headers, $req_data, $options['type'], $options);
+				$redirected->history[] = $return;
+				return $redirected;
+			} elseif ($options['redirected'] >= $options['redirects']) {
+				throw new Exception('Too many redirects', 'toomanyredirects', $return);
+			}
+		}
+
+		$return->redirects = $options['redirected'];
+
+		$options['hooks']->dispatch('requests.after_request', [&$return, $req_headers, $req_data, $options]);
+		return $return;
+	}
+
+	/**
+	 * Callback for `transport.internal.parse_response`
+	 *
+	 * Internal use only. Converts a raw HTTP response to a \WpOrg\Requests\Response
+	 * while still executing a multiple request.
+	 *
+	 * @param string $response Full response text including headers and body (will be overwritten with Response instance)
+	 * @param array $request Request data as passed into {@see \WpOrg\Requests\Requests::request_multiple()}
+	 * @return void `$response` is either set to a \WpOrg\Requests\Response instance, or a \WpOrg\Requests\Exception object
+	 */
+	public static function parse_multiple(&$response, $request) {
+		try {
+			$url      = $request['url'];
+			$headers  = $request['headers'];
+			$data     = $request['data'];
+			$options  = $request['options'];
+			$response = self::parse_response($response, $url, $headers, $data, $options);
+		} catch (Exception $e) {
+			$response = $e;
+		}
+	}
+
+	/**
+	 * Decoded a chunked body as per RFC 2616
+	 *
+	 * @link https://tools.ietf.org/html/rfc2616#section-3.6.1
+	 * @param string $data Chunked body
+	 * @return string Decoded body
+	 */
+	protected static function decode_chunked($data) {
+		if (!preg_match('/^([0-9a-f]+)(?:;(?:[\w-]*)(?:=(?:(?:[\w-]*)*|"(?:[^\r\n])*"))?)*\r\n/i', trim($data))) {
+			return $data;
+		}
+
+		$decoded = '';
+		$encoded = $data;
+
+		while (true) {
+			$is_chunked = (bool) preg_match('/^([0-9a-f]+)(?:;(?:[\w-]*)(?:=(?:(?:[\w-]*)*|"(?:[^\r\n])*"))?)*\r\n/i', $encoded, $matches);
+			if (!$is_chunked) {
+				// Looks like it's not chunked after all
+				return $data;
+			}
+
+			$length = hexdec(trim($matches[1]));
+			if ($length === 0) {
+				// Ignore trailer headers
+				return $decoded;
+			}
+
+			$chunk_length = strlen($matches[0]);
+			$decoded     .= substr($encoded, $chunk_length, $length);
+			$encoded      = substr($encoded, $chunk_length + $length + 2);
+
+			if (trim($encoded) === '0' || empty($encoded)) {
+				return $decoded;
+			}
+		}
+
+		// We'll never actually get down here
+		// @codeCoverageIgnoreStart
+	}
+	// @codeCoverageIgnoreEnd
+
+	/**
+	 * Convert a key => value array to a 'key: value' array for headers
+	 *
+	 * @param iterable $dictionary Dictionary of header values
+	 * @return array List of headers
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not iterable.
+	 */
+	public static function flatten($dictionary) {
+		if (InputValidator::is_iterable($dictionary) === false) {
+			throw InvalidArgument::create(1, '$dictionary', 'iterable', gettype($dictionary));
+		}
+
+		$return = [];
+		foreach ($dictionary as $key => $value) {
+			$return[] = sprintf('%s: %s', $key, $value);
+		}
+
+		return $return;
+	}
+
+	/**
+	 * Decompress an encoded body
+	 *
+	 * Implements gzip, compress and deflate. Guesses which it is by attempting
+	 * to decode.
+	 *
+	 * @param string $data Compressed data in one of the above formats
+	 * @return string Decompressed string
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not a string.
+	 */
+	public static function decompress($data) {
+		if (is_string($data) === false) {
+			throw InvalidArgument::create(1, '$data', 'string', gettype($data));
+		}
+
+		if (trim($data) === '') {
+			// Empty body does not need further processing.
+			return $data;
+		}
+
+		$marker = substr($data, 0, 2);
+		if (!isset(self::$magic_compression_headers[$marker])) {
+			// Not actually compressed. Probably cURL ruining this for us.
+			return $data;
+		}
+
+		if (function_exists('gzdecode')) {
+			$decoded = @gzdecode($data);
+			if ($decoded !== false) {
+				return $decoded;
+			}
+		}
+
+		if (function_exists('gzinflate')) {
+			$decoded = @gzinflate($data);
+			if ($decoded !== false) {
+				return $decoded;
+			}
+		}
+
+		$decoded = self::compatible_gzinflate($data);
+		if ($decoded !== false) {
+			return $decoded;
+		}
+
+		if (function_exists('gzuncompress')) {
+			$decoded = @gzuncompress($data);
+			if ($decoded !== false) {
+				return $decoded;
+			}
+		}
+
+		return $data;
+	}
+
+	/**
+	 * Decompression of deflated string while staying compatible with the majority of servers.
+	 *
+	 * Certain Servers will return deflated data with headers which PHP's gzinflate()
+	 * function cannot handle out of the box. The following function has been created from
+	 * various snippets on the gzinflate() PHP documentation.
+	 *
+	 * Warning: Magic numbers within. Due to the potential different formats that the compressed
+	 * data may be returned in, some "magic offsets" are needed to ensure proper decompression
+	 * takes place. For a simple progmatic way to determine the magic offset in use, see:
+	 * https://core.trac.wordpress.org/ticket/18273
+	 *
+	 * @since 1.6.0
+	 * @link https://core.trac.wordpress.org/ticket/18273
+	 * @link https://www.php.net/gzinflate#70875
+	 * @link https://www.php.net/gzinflate#77336
+	 *
+	 * @param string $gz_data String to decompress.
+	 * @return string|bool False on failure.
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not a string.
+	 */
+	public static function compatible_gzinflate($gz_data) {
+		if (is_string($gz_data) === false) {
+			throw InvalidArgument::create(1, '$gz_data', 'string', gettype($gz_data));
+		}
+
+		if (trim($gz_data) === '') {
+			return false;
+		}
+
+		// Compressed data might contain a full zlib header, if so strip it for
+		// gzinflate()
+		if (substr($gz_data, 0, 3) === "\x1f\x8b\x08") {
+			$i   = 10;
+			$flg = ord(substr($gz_data, 3, 1));
+			if ($flg > 0) {
+				if ($flg & 4) {
+					list($xlen) = unpack('v', substr($gz_data, $i, 2));
+					$i         += 2 + $xlen;
+				}
+
+				if ($flg & 8) {
+					$i = strpos($gz_data, "\0", $i) + 1;
+				}
+
+				if ($flg & 16) {
+					$i = strpos($gz_data, "\0", $i) + 1;
+				}
+
+				if ($flg & 2) {
+					$i += 2;
+				}
+			}
+
+			$decompressed = self::compatible_gzinflate(substr($gz_data, $i));
+			if ($decompressed !== false) {
+				return $decompressed;
+			}
+		}
+
+		// If the data is Huffman Encoded, we must first strip the leading 2
+		// byte Huffman marker for gzinflate()
+		// The response is Huffman coded by many compressors such as
+		// java.util.zip.Deflater, Ruby's Zlib::Deflate, and .NET's
+		// System.IO.Compression.DeflateStream.
+		//
+		// See https://decompres.blogspot.com/ for a quick explanation of this
+		// data type
+		$huffman_encoded = false;
+
+		// low nibble of first byte should be 0x08
+		list(, $first_nibble) = unpack('h', $gz_data);
+
+		// First 2 bytes should be divisible by 0x1F
+		list(, $first_two_bytes) = unpack('n', $gz_data);
+
+		if ($first_nibble === 0x08 && ($first_two_bytes % 0x1F) === 0) {
+			$huffman_encoded = true;
+		}
+
+		if ($huffman_encoded) {
+			$decompressed = @gzinflate(substr($gz_data, 2));
+			if ($decompressed !== false) {
+				return $decompressed;
+			}
+		}
+
+		if (substr($gz_data, 0, 4) === "\x50\x4b\x03\x04") {
+			// ZIP file format header
+			// Offset 6: 2 bytes, General-purpose field
+			// Offset 26: 2 bytes, filename length
+			// Offset 28: 2 bytes, optional field length
+			// Offset 30: Filename field, followed by optional field, followed
+			// immediately by data
+			list(, $general_purpose_flag) = unpack('v', substr($gz_data, 6, 2));
+
+			// If the file has been compressed on the fly, 0x08 bit is set of
+			// the general purpose field. We can use this to differentiate
+			// between a compressed document, and a ZIP file
+			$zip_compressed_on_the_fly = ((0x08 & $general_purpose_flag) === 0x08);
+
+			if (!$zip_compressed_on_the_fly) {
+				// Don't attempt to decode a compressed zip file
+				return $gz_data;
+			}
+
+			// Determine the first byte of data, based on the above ZIP header
+			// offsets:
+			$first_file_start = array_sum(unpack('v2', substr($gz_data, 26, 4)));
+			$decompressed     = @gzinflate(substr($gz_data, 30 + $first_file_start));
+			if ($decompressed !== false) {
+				return $decompressed;
+			}
+
+			return false;
+		}
+
+		// Finally fall back to straight gzinflate
+		$decompressed = @gzinflate($gz_data);
+		if ($decompressed !== false) {
+			return $decompressed;
+		}
+
+		// Fallback for all above failing, not expected, but included for
+		// debugging and preventing regressions and to track stats
+		$decompressed = @gzinflate(substr($gz_data, 2));
+		if ($decompressed !== false) {
+			return $decompressed;
+		}
+
+		return false;
+	}
+}
diff --git a/wp-includes/Requests/src/Response.php b/wp-includes/Requests/src/Response.php
new file mode 100644
index 0000000000..8964521a81
--- /dev/null
+++ b/wp-includes/Requests/src/Response.php
@@ -0,0 +1,165 @@
+<?php
+/**
+ * HTTP response class
+ *
+ * Contains a response from \WpOrg\Requests\Requests::request()
+ *
+ * @package Requests
+ */
+
+namespace WpOrg\Requests;
+
+use WpOrg\Requests\Cookie\Jar;
+use WpOrg\Requests\Exception;
+use WpOrg\Requests\Exception\Http;
+use WpOrg\Requests\Response\Headers;
+
+/**
+ * HTTP response class
+ *
+ * Contains a response from \WpOrg\Requests\Requests::request()
+ *
+ * @package Requests
+ */
+class Response {
+
+	/**
+	 * Response body
+	 *
+	 * @var string
+	 */
+	public $body = '';
+
+	/**
+	 * Raw HTTP data from the transport
+	 *
+	 * @var string
+	 */
+	public $raw = '';
+
+	/**
+	 * Headers, as an associative array
+	 *
+	 * @var \WpOrg\Requests\Response\Headers Array-like object representing headers
+	 */
+	public $headers = [];
+
+	/**
+	 * Status code, false if non-blocking
+	 *
+	 * @var integer|boolean
+	 */
+	public $status_code = false;
+
+	/**
+	 * Protocol version, false if non-blocking
+	 *
+	 * @var float|boolean
+	 */
+	public $protocol_version = false;
+
+	/**
+	 * Whether the request succeeded or not
+	 *
+	 * @var boolean
+	 */
+	public $success = false;
+
+	/**
+	 * Number of redirects the request used
+	 *
+	 * @var integer
+	 */
+	public $redirects = 0;
+
+	/**
+	 * URL requested
+	 *
+	 * @var string
+	 */
+	public $url = '';
+
+	/**
+	 * Previous requests (from redirects)
+	 *
+	 * @var array Array of \WpOrg\Requests\Response objects
+	 */
+	public $history = [];
+
+	/**
+	 * Cookies from the request
+	 *
+	 * @var \WpOrg\Requests\Cookie\Jar Array-like object representing a cookie jar
+	 */
+	public $cookies = [];
+
+	/**
+	 * Constructor
+	 */
+	public function __construct() {
+		$this->headers = new Headers();
+		$this->cookies = new Jar();
+	}
+
+	/**
+	 * Is the response a redirect?
+	 *
+	 * @return boolean True if redirect (3xx status), false if not.
+	 */
+	public function is_redirect() {
+		$code = $this->status_code;
+		return in_array($code, [300, 301, 302, 303, 307], true) || $code > 307 && $code < 400;
+	}
+
+	/**
+	 * Throws an exception if the request was not successful
+	 *
+	 * @param boolean $allow_redirects Set to false to throw on a 3xx as well
+	 *
+	 * @throws \WpOrg\Requests\Exception If `$allow_redirects` is false, and code is 3xx (`response.no_redirects`)
+	 * @throws \WpOrg\Requests\Exception\Http On non-successful status code. Exception class corresponds to "Status" + code (e.g. {@see \WpOrg\Requests\Exception\Http\Status404})
+	 */
+	public function throw_for_status($allow_redirects = true) {
+		if ($this->is_redirect()) {
+			if ($allow_redirects !== true) {
+				throw new Exception('Redirection not allowed', 'response.no_redirects', $this);
+			}
+		} elseif (!$this->success) {
+			$exception = Http::get_class($this->status_code);
+			throw new $exception(null, $this);
+		}
+	}
+
+	/**
+	 * JSON decode the response body.
+	 *
+	 * The method parameters are the same as those for the PHP native `json_decode()` function.
+	 *
+	 * @link https://php.net/json-decode
+	 *
+	 * @param ?bool $associative Optional. When `true`, JSON objects will be returned as associative arrays;
+	 *                           When `false`, JSON objects will be returned as objects.
+	 *                           When `null`, JSON objects will be returned as associative arrays
+	 *                           or objects depending on whether `JSON_OBJECT_AS_ARRAY` is set in the flags.
+	 *                           Defaults to `true` (in contrast to the PHP native default of `null`).
+	 * @param int   $depth       Optional. Maximum nesting depth of the structure being decoded.
+	 *                           Defaults to `512`.
+	 * @param int   $options     Optional. Bitmask of JSON_BIGINT_AS_STRING, JSON_INVALID_UTF8_IGNORE,
+	 *                           JSON_INVALID_UTF8_SUBSTITUTE, JSON_OBJECT_AS_ARRAY, JSON_THROW_ON_ERROR.
+	 *                           Defaults to `0` (no options set).
+	 *
+	 * @return array
+	 *
+	 * @throws \WpOrg\Requests\Exception If `$this->body` is not valid json.
+	 */
+	public function decode_body($associative = true, $depth = 512, $options = 0) {
+		$data = json_decode($this->body, $associative, $depth, $options);
+
+		if (json_last_error() !== JSON_ERROR_NONE) {
+			$last_error = json_last_error_msg();
+			throw new Exception('Unable to parse JSON data: ' . $last_error, 'response.invalid', $this);
+		}
+
+		return $data;
+	}
+}
diff --git a/wp-includes/Requests/src/Response/Headers.php b/wp-includes/Requests/src/Response/Headers.php
new file mode 100644
index 0000000000..eb4f68736b
--- /dev/null
+++ b/wp-includes/Requests/src/Response/Headers.php
@@ -0,0 +1,124 @@
+<?php
+/**
+ * Case-insensitive dictionary, suitable for HTTP headers
+ *
+ * @package Requests
+ */
+
+namespace WpOrg\Requests\Response;
+
+use WpOrg\Requests\Exception;
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Utility\CaseInsensitiveDictionary;
+use WpOrg\Requests\Utility\FilteredIterator;
+
+/**
+ * Case-insensitive dictionary, suitable for HTTP headers
+ *
+ * @package Requests
+ */
+class Headers extends CaseInsensitiveDictionary {
+	/**
+	 * Get the given header
+	 *
+	 * Unlike {@see \WpOrg\Requests\Response\Headers::getValues()}, this returns a string. If there are
+	 * multiple values, it concatenates them with a comma as per RFC2616.
+	 *
+	 * Avoid using this where commas may be used unquoted in values, such as
+	 * Set-Cookie headers.
+	 *
+	 * @param string $offset
+	 * @return string|null Header value
+	 */
+	public function offsetGet($offset) {
+		if (is_string($offset)) {
+			$offset = strtolower($offset);
+		}
+
+		if (!isset($this->data[$offset])) {
+			return null;
+		}
+
+		return $this->flatten($this->data[$offset]);
+	}
+
+	/**
+	 * Set the given item
+	 *
+	 * @param string $offset Item name
+	 * @param string $value Item value
+	 *
+	 * @throws \WpOrg\Requests\Exception On attempting to use dictionary as list (`invalidset`)
+	 */
+	public function offsetSet($offset, $value) {
+		if ($offset === null) {
+			throw new Exception('Object is a dictionary, not a list', 'invalidset');
+		}
+
+		if (is_string($offset)) {
+			$offset = strtolower($offset);
+		}
+
+		if (!isset($this->data[$offset])) {
+			$this->data[$offset] = [];
+		}
+
+		$this->data[$offset][] = $value;
+	}
+
+	/**
+	 * Get all values for a given header
+	 *
+	 * @param string $offset
+	 * @return array|null Header values
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not valid as an array key.
+	 */
+	public function getValues($offset) {
+		if (!is_string($offset) && !is_int($offset)) {
+			throw InvalidArgument::create(1, '$offset', 'string|int', gettype($offset));
+		}
+
+		$offset = strtolower($offset);
+		if (!isset($this->data[$offset])) {
+			return null;
+		}
+
+		return $this->data[$offset];
+	}
+
+	/**
+	 * Flattens a value into a string
+	 *
+	 * Converts an array into a string by imploding values with a comma, as per
+	 * RFC2616's rules for folding headers.
+	 *
+	 * @param string|array $value Value to flatten
+	 * @return string Flattened value
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not a string or an array.
+	 */
+	public function flatten($value) {
+		if (is_string($value)) {
+			return $value;
+		}
+
+		if (is_array($value)) {
+			return implode(',', $value);
+		}
+
+		throw InvalidArgument::create(1, '$value', 'string|array', gettype($value));
+	}
+
+	/**
+	 * Get an iterator for the data
+	 *
+	 * Converts the internally stored values to a comma-separated string if there is more
+	 * than one value for a key.
+	 *
+	 * @return \ArrayIterator
+	 */
+	public function getIterator() {
+		return new FilteredIterator($this->data, [$this, 'flatten']);
+	}
+}
diff --git a/wp-includes/Requests/Session.php b/wp-includes/Requests/src/Session.php
similarity index 51%
rename from wp-includes/Requests/Session.php
rename to wp-includes/Requests/src/Session.php
index b2e10991d6..000d2526d4 100644
--- a/wp-includes/Requests/Session.php
+++ b/wp-includes/Requests/src/Session.php
@@ -2,10 +2,17 @@
 /**
  * Session handler for persistent requests and default parameters
  *
- * @package Requests
- * @subpackage Session Handler
+ * @package Requests\SessionHandler
  */
 
+namespace WpOrg\Requests;
+
+use WpOrg\Requests\Cookie\Jar;
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Iri;
+use WpOrg\Requests\Requests;
+use WpOrg\Requests\Utility\InputValidator;
+
 /**
  * Session handler for persistent requests and default parameters
  *
@@ -14,10 +21,9 @@
  * with all subrequests resolved from this. Base options can be set (including
  * a shared cookie jar), then overridden for individual requests.
  *
- * @package Requests
- * @subpackage Session Handler
+ * @package Requests\SessionHandler
  */
-class Requests_Session {
+class Session {
 	/**
 	 * Base URL for requests
 	 *
@@ -32,7 +38,7 @@ class Requests_Session {
 	 *
 	 * @var array
 	 */
-	public $headers = array();
+	public $headers = [];
 
 	/**
 	 * Base data for requests
@@ -42,7 +48,7 @@ class Requests_Session {
 	 *
 	 * @var array
 	 */
-	public $data = array();
+	public $data = [];
 
 	/**
 	 * Base options for requests
@@ -55,36 +61,57 @@ class Requests_Session {
 	 *
 	 * @var array
 	 */
-	public $options = array();
+	public $options = [];
 
 	/**
 	 * Create a new session
 	 *
-	 * @param string|null $url Base URL for requests
+	 * @param string|Stringable|null $url Base URL for requests
 	 * @param array $headers Default headers for requests
 	 * @param array $data Default data for requests
 	 * @param array $options Default options for requests
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $url argument is not a string, Stringable or null.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $headers argument is not an array.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $data argument is not an array.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $options argument is not an array.
 	 */
-	public function __construct($url = null, $headers = array(), $data = array(), $options = array()) {
+	public function __construct($url = null, $headers = [], $data = [], $options = []) {
+		if ($url !== null && InputValidator::is_string_or_stringable($url) === false) {
+			throw InvalidArgument::create(1, '$url', 'string|Stringable|null', gettype($url));
+		}
+
+		if (is_array($headers) === false) {
+			throw InvalidArgument::create(2, '$headers', 'array', gettype($headers));
+		}
+
+		if (is_array($data) === false) {
+			throw InvalidArgument::create(3, '$data', 'array', gettype($data));
+		}
+
+		if (is_array($options) === false) {
+			throw InvalidArgument::create(4, '$options', 'array', gettype($options));
+		}
+
 		$this->url     = $url;
 		$this->headers = $headers;
 		$this->data    = $data;
 		$this->options = $options;
 
 		if (empty($this->options['cookies'])) {
-			$this->options['cookies'] = new Requests_Cookie_Jar();
+			$this->options['cookies'] = new Jar();
 		}
 	}
 
 	/**
 	 * Get a property's value
 	 *
-	 * @param string $key Property key
+	 * @param string $name Property name.
 	 * @return mixed|null Property value, null if none found
 	 */
-	public function __get($key) {
-		if (isset($this->options[$key])) {
-			return $this->options[$key];
+	public function __get($name) {
+		if (isset($this->options[$name])) {
+			return $this->options[$name];
 		}
 
 		return null;
@@ -93,93 +120,91 @@ class Requests_Session {
 	/**
 	 * Set a property's value
 	 *
-	 * @param string $key Property key
+	 * @param string $name Property name.
 	 * @param mixed $value Property value
 	 */
-	public function __set($key, $value) {
-		$this->options[$key] = $value;
+	public function __set($name, $value) {
+		$this->options[$name] = $value;
 	}
 
 	/**
 	 * Remove a property's value
 	 *
-	 * @param string $key Property key
+	 * @param string $name Property name.
 	 */
-	public function __isset($key) {
-		return isset($this->options[$key]);
+	public function __isset($name) {
+		return isset($this->options[$name]);
 	}
 
 	/**
 	 * Remove a property's value
 	 *
-	 * @param string $key Property key
+	 * @param string $name Property name.
 	 */
-	public function __unset($key) {
-		if (isset($this->options[$key])) {
-			unset($this->options[$key]);
-		}
+	public function __unset($name) {
+		unset($this->options[$name]);
 	}
 
 	/**#@+
-	 * @see request()
+	 * @see \WpOrg\Requests\Session::request()
 	 * @param string $url
 	 * @param array $headers
 	 * @param array $options
-	 * @return Requests_Response
+	 * @return \WpOrg\Requests\Response
 	 */
 	/**
 	 * Send a GET request
 	 */
-	public function get($url, $headers = array(), $options = array()) {
+	public function get($url, $headers = [], $options = []) {
 		return $this->request($url, $headers, null, Requests::GET, $options);
 	}
 
 	/**
 	 * Send a HEAD request
 	 */
-	public function head($url, $headers = array(), $options = array()) {
+	public function head($url, $headers = [], $options = []) {
 		return $this->request($url, $headers, null, Requests::HEAD, $options);
 	}
 
 	/**
 	 * Send a DELETE request
 	 */
-	public function delete($url, $headers = array(), $options = array()) {
+	public function delete($url, $headers = [], $options = []) {
 		return $this->request($url, $headers, null, Requests::DELETE, $options);
 	}
 	/**#@-*/
 
 	/**#@+
-	 * @see request()
+	 * @see \WpOrg\Requests\Session::request()
 	 * @param string $url
 	 * @param array $headers
 	 * @param array $data
 	 * @param array $options
-	 * @return Requests_Response
+	 * @return \WpOrg\Requests\Response
 	 */
 	/**
 	 * Send a POST request
 	 */
-	public function post($url, $headers = array(), $data = array(), $options = array()) {
+	public function post($url, $headers = [], $data = [], $options = []) {
 		return $this->request($url, $headers, $data, Requests::POST, $options);
 	}
 
 	/**
 	 * Send a PUT request
 	 */
-	public function put($url, $headers = array(), $data = array(), $options = array()) {
+	public function put($url, $headers = [], $data = [], $options = []) {
 		return $this->request($url, $headers, $data, Requests::PUT, $options);
 	}
 
 	/**
 	 * Send a PATCH request
 	 *
-	 * Note: Unlike {@see post} and {@see put}, `$headers` is required, as the
-	 * specification recommends that should send an ETag
+	 * Note: Unlike {@see \WpOrg\Requests\Session::post()} and {@see \WpOrg\Requests\Session::put()},
+	 * `$headers` is required, as the specification recommends that should send an ETag
 	 *
 	 * @link https://tools.ietf.org/html/rfc5789
 	 */
-	public function patch($url, $headers, $data = array(), $options = array()) {
+	public function patch($url, $headers, $data = [], $options = []) {
 		return $this->request($url, $headers, $data, Requests::PATCH, $options);
 	}
 	/**#@-*/
@@ -190,18 +215,18 @@ class Requests_Session {
 	 * This method initiates a request and sends it via a transport before
 	 * parsing.
 	 *
-	 * @see Requests::request()
-	 *
-	 * @throws Requests_Exception On invalid URLs (`nonhttp`)
+	 * @see \WpOrg\Requests\Requests::request()
 	 *
 	 * @param string $url URL to request
 	 * @param array $headers Extra headers to send with the request
 	 * @param array|null $data Data to send either as a query string for GET/HEAD requests, or in the body for POST requests
-	 * @param string $type HTTP request type (use Requests constants)
-	 * @param array $options Options for the request (see {@see Requests::request})
-	 * @return Requests_Response
+	 * @param string $type HTTP request type (use \WpOrg\Requests\Requests constants)
+	 * @param array $options Options for the request (see {@see \WpOrg\Requests\Requests::request()})
+	 * @return \WpOrg\Requests\Response
+	 *
+	 * @throws \WpOrg\Requests\Exception On invalid URLs (`nonhttp`)
 	 */
-	public function request($url, $headers = array(), $data = array(), $type = Requests::GET, $options = array()) {
+	public function request($url, $headers = [], $data = [], $type = Requests::GET, $options = []) {
 		$request = $this->merge_request(compact('url', 'headers', 'data', 'options'));
 
 		return Requests::request($request['url'], $request['headers'], $request['data'], $type, $request['options']);
@@ -210,13 +235,24 @@ class Requests_Session {
 	/**
 	 * Send multiple HTTP requests simultaneously
 	 *
-	 * @see Requests::request_multiple()
+	 * @see \WpOrg\Requests\Requests::request_multiple()
 	 *
-	 * @param array $requests Requests data (see {@see Requests::request_multiple})
-	 * @param array $options Global and default options (see {@see Requests::request})
-	 * @return array Responses (either Requests_Response or a Requests_Exception object)
+	 * @param array $requests Requests data (see {@see \WpOrg\Requests\Requests::request_multiple()})
+	 * @param array $options Global and default options (see {@see \WpOrg\Requests\Requests::request()})
+	 * @return array Responses (either \WpOrg\Requests\Response or a \WpOrg\Requests\Exception object)
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $requests argument is not an array or iterable object with array access.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $options argument is not an array.
 	 */
-	public function request_multiple($requests, $options = array()) {
+	public function request_multiple($requests, $options = []) {
+		if (InputValidator::has_array_access($requests) === false || InputValidator::is_iterable($requests) === false) {
+			throw InvalidArgument::create(1, '$requests', 'array|ArrayAccess&Traversable', gettype($requests));
+		}
+
+		if (is_array($options) === false) {
+			throw InvalidArgument::create(2, '$options', 'array', gettype($options));
+		}
+
 		foreach ($requests as $key => $request) {
 			$requests[$key] = $this->merge_request($request, false);
 		}
@@ -232,31 +268,31 @@ class Requests_Session {
 	/**
 	 * Merge a request's data with the default data
 	 *
-	 * @param array $request Request data (same form as {@see request_multiple})
+	 * @param array $request Request data (same form as {@see \WpOrg\Requests\Session::request_multiple()})
 	 * @param boolean $merge_options Should we merge options as well?
 	 * @return array Request data
 	 */
 	protected function merge_request($request, $merge_options = true) {
 		if ($this->url !== null) {
-			$request['url'] = Requests_IRI::absolutize($this->url, $request['url']);
+			$request['url'] = Iri::absolutize($this->url, $request['url']);
 			$request['url'] = $request['url']->uri;
 		}
 
 		if (empty($request['headers'])) {
-			$request['headers'] = array();
+			$request['headers'] = [];
 		}
+
 		$request['headers'] = array_merge($this->headers, $request['headers']);
 
 		if (empty($request['data'])) {
 			if (is_array($this->data)) {
 				$request['data'] = $this->data;
 			}
-		}
-		elseif (is_array($request['data']) && is_array($this->data)) {
+		} elseif (is_array($request['data']) && is_array($this->data)) {
 			$request['data'] = array_merge($this->data, $request['data']);
 		}
 
-		if ($merge_options !== false) {
+		if ($merge_options === true) {
 			$request['options'] = array_merge($this->options, $request['options']);
 
 			// Disallow forcing the type, as that's a per request setting
diff --git a/wp-includes/Requests/SSL.php b/wp-includes/Requests/src/Ssl.php
similarity index 55%
rename from wp-includes/Requests/SSL.php
rename to wp-includes/Requests/src/Ssl.php
index f7ecf3fbdb..99da11d8f7 100644
--- a/wp-includes/Requests/SSL.php
+++ b/wp-includes/Requests/src/Ssl.php
@@ -2,37 +2,49 @@
 /**
  * SSL utilities for Requests
  *
- * @package Requests
- * @subpackage Utilities
+ * @package Requests\Utilities
  */
 
+namespace WpOrg\Requests;
+
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Utility\InputValidator;
+
 /**
  * SSL utilities for Requests
  *
  * Collection of utilities for working with and verifying SSL certificates.
  *
- * @package Requests
- * @subpackage Utilities
+ * @package Requests\Utilities
  */
-class Requests_SSL {
+final class Ssl {
 	/**
 	 * Verify the certificate against common name and subject alternative names
 	 *
 	 * Unfortunately, PHP doesn't check the certificate against the alternative
 	 * names, leading things like 'https://www.github.com/' to be invalid.
 	 *
-	 * @see https://tools.ietf.org/html/rfc2818#section-3.1 RFC2818, Section 3.1
+	 * @link https://tools.ietf.org/html/rfc2818#section-3.1 RFC2818, Section 3.1
 	 *
-	 * @throws Requests_Exception On not obtaining a match for the host (`fsockopen.ssl.no_match`)
-	 * @param string $host Host name to verify against
+	 * @param string|Stringable $host Host name to verify against
 	 * @param array $cert Certificate data from openssl_x509_parse()
 	 * @return bool
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $host argument is not a string or a stringable object.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $cert argument is not an array or array accessible.
 	 */
 	public static function verify_certificate($host, $cert) {
+		if (InputValidator::is_string_or_stringable($host) === false) {
+			throw InvalidArgument::create(1, '$host', 'string|Stringable', gettype($host));
+		}
+
+		if (InputValidator::has_array_access($cert) === false) {
+			throw InvalidArgument::create(2, '$cert', 'array|ArrayAccess', gettype($cert));
+		}
+
 		$has_dns_alt = false;
 
 		// Check the subjectAltName
-		if (!empty($cert['extensions']) && !empty($cert['extensions']['subjectAltName'])) {
+		if (!empty($cert['extensions']['subjectAltName'])) {
 			$altnames = explode(',', $cert['extensions']['subjectAltName']);
 			foreach ($altnames as $altname) {
 				$altname = trim($altname);
@@ -50,15 +62,17 @@ class Requests_SSL {
 					return true;
 				}
 			}
+
+			if ($has_dns_alt === true) {
+				return false;
+			}
 		}
 
 		// Fall back to checking the common name if we didn't get any dNSName
 		// alt names, as per RFC2818
-		if (!$has_dns_alt && !empty($cert['subject']['CN'])) {
+		if (!empty($cert['subject']['CN'])) {
 			// Check for a match
-			if (self::match_domain($host, $cert['subject']['CN']) === true) {
-				return true;
-			}
+			return (self::match_domain($host, $cert['subject']['CN']) === true);
 		}
 
 		return false;
@@ -77,11 +91,29 @@ class Requests_SSL {
 	 * character to be the full first component; that is, with the exclusion of
 	 * the third rule.
 	 *
-	 * @param string $reference Reference dNSName
+	 * @param string|Stringable $reference Reference dNSName
 	 * @return boolean Is the name valid?
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed argument is not a string or a stringable object.
 	 */
 	public static function verify_reference_name($reference) {
+		if (InputValidator::is_string_or_stringable($reference) === false) {
+			throw InvalidArgument::create(1, '$reference', 'string|Stringable', gettype($reference));
+		}
+
+		if ($reference === '') {
+			return false;
+		}
+
+		if (preg_match('`\s`', $reference) > 0) {
+			// Whitespace detected. This can never be a dNSName.
+			return false;
+		}
+
 		$parts = explode('.', $reference);
+		if ($parts !== array_filter($parts)) {
+			// DNSName cannot contain two dots next to each other.
+			return false;
+		}
 
 		// Check the first part of the name
 		$first = array_shift($parts);
@@ -112,29 +144,35 @@ class Requests_SSL {
 	/**
 	 * Match a hostname against a dNSName reference
 	 *
-	 * @param string $host Requested host
-	 * @param string $reference dNSName to match against
+	 * @param string|Stringable $host Requested host
+	 * @param string|Stringable $reference dNSName to match against
 	 * @return boolean Does the domain match?
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When either of the passed arguments is not a string or a stringable object.
 	 */
 	public static function match_domain($host, $reference) {
+		if (InputValidator::is_string_or_stringable($host) === false) {
+			throw InvalidArgument::create(1, '$host', 'string|Stringable', gettype($host));
+		}
+
 		// Check if the reference is blocklisted first
 		if (self::verify_reference_name($reference) !== true) {
 			return false;
 		}
 
 		// Check for a direct match
-		if ($host === $reference) {
+		if ((string) $host === (string) $reference) {
 			return true;
 		}
 
 		// Calculate the valid wildcard match if the host is not an IP address
-		// Also validates that the host has 3 parts or more, as per Firefox's
-		// ruleset.
+		// Also validates that the host has 3 parts or more, as per Firefox's ruleset,
+		// as a wildcard reference is only allowed with 3 parts or more, so the
+		// comparison will never match if host doesn't contain 3 parts or more as well.
 		if (ip2long($host) === false) {
 			$parts    = explode('.', $host);
 			$parts[0] = '*';
 			$wildcard = implode('.', $parts);
-			if ($wildcard === $reference) {
+			if ($wildcard === (string) $reference) {
 				return true;
 			}
 		}
diff --git a/wp-includes/Requests/src/Transport.php b/wp-includes/Requests/src/Transport.php
new file mode 100644
index 0000000000..f2e1c6ed73
--- /dev/null
+++ b/wp-includes/Requests/src/Transport.php
@@ -0,0 +1,45 @@
+<?php
+/**
+ * Base HTTP transport
+ *
+ * @package Requests\Transport
+ */
+
+namespace WpOrg\Requests;
+
+/**
+ * Base HTTP transport
+ *
+ * @package Requests\Transport
+ */
+interface Transport {
+	/**
+	 * Perform a request
+	 *
+	 * @param string $url URL to request
+	 * @param array $headers Associative array of request headers
+	 * @param string|array $data Data to send either as the POST body, or as parameters in the URL for a GET/HEAD
+	 * @param array $options Request options, see {@see \WpOrg\Requests\Requests::response()} for documentation
+	 * @return string Raw HTTP result
+	 */
+	public function request($url, $headers = [], $data = [], $options = []);
+
+	/**
+	 * Send multiple requests simultaneously
+	 *
+	 * @param array $requests Request data (array of 'url', 'headers', 'data', 'options') as per {@see \WpOrg\Requests\Transport::request()}
+	 * @param array $options Global options, see {@see \WpOrg\Requests\Requests::response()} for documentation
+	 * @return array Array of \WpOrg\Requests\Response objects (may contain \WpOrg\Requests\Exception or string responses as well)
+	 */
+	public function request_multiple($requests, $options);
+
+	/**
+	 * Self-test whether the transport can be used.
+	 *
+	 * The available capabilities to test for can be found in {@see \WpOrg\Requests\Capability}.
+	 *
+	 * @param array<string, bool> $capabilities Optional. Associative array of capabilities to test against, i.e. `['<capability>' => true]`.
+	 * @return bool Whether the transport can be used.
+	 */
+	public static function test($capabilities = []);
+}
diff --git a/wp-includes/Requests/Transport/cURL.php b/wp-includes/Requests/src/Transport/Curl.php
similarity index 69%
rename from wp-includes/Requests/Transport/cURL.php
rename to wp-includes/Requests/src/Transport/Curl.php
index 01bcf3b719..8b0a13080e 100644
--- a/wp-includes/Requests/Transport/cURL.php
+++ b/wp-includes/Requests/src/Transport/Curl.php
@@ -2,17 +2,27 @@
 /**
  * cURL HTTP transport
  *
- * @package Requests
- * @subpackage Transport
+ * @package Requests\Transport
  */
 
+namespace WpOrg\Requests\Transport;
+
+use RecursiveArrayIterator;
+use RecursiveIteratorIterator;
+use WpOrg\Requests\Capability;
+use WpOrg\Requests\Exception;
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Exception\Transport\Curl as CurlException;
+use WpOrg\Requests\Requests;
+use WpOrg\Requests\Transport;
+use WpOrg\Requests\Utility\InputValidator;
+
 /**
  * cURL HTTP transport
  *
- * @package Requests
- * @subpackage Transport
+ * @package Requests\Transport
  */
-class Requests_Transport_cURL implements Requests_Transport {
+final class Curl implements Transport {
 	const CURL_7_10_5 = 0x070A05;
 	const CURL_7_16_2 = 0x071002;
 
@@ -33,7 +43,7 @@ class Requests_Transport_cURL implements Requests_Transport {
 	/**
 	 * Information on the current request
 	 *
-	 * @var array cURL information array, see {@see https://secure.php.net/curl_getinfo}
+	 * @var array cURL information array, see {@link https://www.php.net/curl_getinfo}
 	 */
 	public $info;
 
@@ -47,44 +57,44 @@ class Requests_Transport_cURL implements Requests_Transport {
 	/**
 	 * cURL handle
 	 *
-	 * @var resource
+	 * @var resource|\CurlHandle Resource in PHP < 8.0, Instance of CurlHandle in PHP >= 8.0.
 	 */
-	protected $handle;
+	private $handle;
 
 	/**
 	 * Hook dispatcher instance
 	 *
-	 * @var Requests_Hooks
+	 * @var \WpOrg\Requests\Hooks
 	 */
-	protected $hooks;
+	private $hooks;
 
 	/**
 	 * Have we finished the headers yet?
 	 *
 	 * @var boolean
 	 */
-	protected $done_headers = false;
+	private $done_headers = false;
 
 	/**
 	 * If streaming to a file, keep the file pointer
 	 *
 	 * @var resource
 	 */
-	protected $stream_handle;
+	private $stream_handle;
 
 	/**
 	 * How many bytes are in the response body?
 	 *
 	 * @var int
 	 */
-	protected $response_bytes;
+	private $response_bytes;
 
 	/**
 	 * What's the maximum number of bytes we should keep?
 	 *
 	 * @var int|bool Byte count, or false if no limit.
 	 */
-	protected $response_byte_limit;
+	private $response_byte_limit;
 
 	/**
 	 * Constructor
@@ -99,10 +109,12 @@ class Requests_Transport_cURL implements Requests_Transport {
 		if ($this->version >= self::CURL_7_10_5) {
 			curl_setopt($this->handle, CURLOPT_ENCODING, '');
 		}
+
 		if (defined('CURLOPT_PROTOCOLS')) {
 			// phpcs:ignore PHPCompatibility.Constants.NewConstants.curlopt_protocolsFound
 			curl_setopt($this->handle, CURLOPT_PROTOCOLS, CURLPROTO_HTTP | CURLPROTO_HTTPS);
 		}
+
 		if (defined('CURLOPT_REDIR_PROTOCOLS')) {
 			// phpcs:ignore PHPCompatibility.Constants.NewConstants.curlopt_redir_protocolsFound
 			curl_setopt($this->handle, CURLOPT_REDIR_PROTOCOLS, CURLPROTO_HTTP | CURLPROTO_HTTPS);
@@ -121,23 +133,52 @@ class Requests_Transport_cURL implements Requests_Transport {
 	/**
 	 * Perform a request
 	 *
-	 * @throws Requests_Exception On a cURL error (`curlerror`)
-	 *
-	 * @param string $url URL to request
+	 * @param string|Stringable $url URL to request
 	 * @param array $headers Associative array of request headers
 	 * @param string|array $data Data to send either as the POST body, or as parameters in the URL for a GET/HEAD
-	 * @param array $options Request options, see {@see Requests::response()} for documentation
+	 * @param array $options Request options, see {@see \WpOrg\Requests\Requests::response()} for documentation
 	 * @return string Raw HTTP result
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $url argument is not a string or Stringable.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $headers argument is not an array.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $data parameter is not an array or string.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $options argument is not an array.
+	 * @throws \WpOrg\Requests\Exception       On a cURL error (`curlerror`)
 	 */
-	public function request($url, $headers = array(), $data = array(), $options = array()) {
+	public function request($url, $headers = [], $data = [], $options = []) {
+		if (InputValidator::is_string_or_stringable($url) === false) {
+			throw InvalidArgument::create(1, '$url', 'string|Stringable', gettype($url));
+		}
+
+		if (is_array($headers) === false) {
+			throw InvalidArgument::create(2, '$headers', 'array', gettype($headers));
+		}
+
+		if (!is_array($data) && !is_string($data)) {
+			if ($data === null) {
+				$data = '';
+			} else {
+				throw InvalidArgument::create(3, '$data', 'array|string', gettype($data));
+			}
+		}
+
+		if (is_array($options) === false) {
+			throw InvalidArgument::create(4, '$options', 'array', gettype($options));
+		}
+
 		$this->hooks = $options['hooks'];
 
 		$this->setup_handle($url, $headers, $data, $options);
 
-		$options['hooks']->dispatch('curl.before_send', array(&$this->handle));
+		$options['hooks']->dispatch('curl.before_send', [&$this->handle]);
 
 		if ($options['filename'] !== false) {
-			$this->stream_handle = fopen($options['filename'], 'wb');
+			// phpcs:ignore WordPress.PHP.NoSilencedErrors -- Silenced the PHP native warning in favour of throwing an exception.
+			$this->stream_handle = @fopen($options['filename'], 'wb');
+			if ($this->stream_handle === false) {
+				$error = error_get_last();
+				throw new Exception($error['message'], 'fopen');
+			}
 		}
 
 		$this->response_data       = '';
@@ -151,8 +192,7 @@ class Requests_Transport_cURL implements Requests_Transport {
 			if ($options['verify'] === false) {
 				curl_setopt($this->handle, CURLOPT_SSL_VERIFYHOST, 0);
 				curl_setopt($this->handle, CURLOPT_SSL_VERIFYPEER, 0);
-			}
-			elseif (is_string($options['verify'])) {
+			} elseif (is_string($options['verify'])) {
 				curl_setopt($this->handle, CURLOPT_CAINFO, $options['verify']);
 			}
 		}
@@ -164,9 +204,9 @@ class Requests_Transport_cURL implements Requests_Transport {
 		curl_exec($this->handle);
 		$response = $this->response_data;
 
-		$options['hooks']->dispatch('curl.after_send', array());
+		$options['hooks']->dispatch('curl.after_send', []);
 
-		if (curl_errno($this->handle) === 23 || curl_errno($this->handle) === 61) {
+		if (curl_errno($this->handle) === CURLE_WRITE_ERROR || curl_errno($this->handle) === CURLE_BAD_CONTENT_ENCODING) {
 			// Reset encoding and try again
 			curl_setopt($this->handle, CURLOPT_ENCODING, 'none');
 
@@ -179,7 +219,7 @@ class Requests_Transport_cURL implements Requests_Transport {
 		$this->process_response($response, $options);
 
 		// Need to remove the $this reference from the curl handle.
-		// Otherwise Requests_Transport_cURL wont be garbage collected and the curl_close() will never be called.
+		// Otherwise \WpOrg\Requests\Transport\Curl won't be garbage collected and the curl_close() will never be called.
 		curl_setopt($this->handle, CURLOPT_HEADERFUNCTION, null);
 		curl_setopt($this->handle, CURLOPT_WRITEFUNCTION, null);
 
@@ -191,41 +231,51 @@ class Requests_Transport_cURL implements Requests_Transport {
 	 *
 	 * @param array $requests Request data
 	 * @param array $options Global options
-	 * @return array Array of Requests_Response objects (may contain Requests_Exception or string responses as well)
+	 * @return array Array of \WpOrg\Requests\Response objects (may contain \WpOrg\Requests\Exception or string responses as well)
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $requests argument is not an array or iterable object with array access.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $options argument is not an array.
 	 */
 	public function request_multiple($requests, $options) {
 		// If you're not requesting, we can't get any responses ¯\_(ツ)_/¯
 		if (empty($requests)) {
-			return array();
+			return [];
+		}
+
+		if (InputValidator::has_array_access($requests) === false || InputValidator::is_iterable($requests) === false) {
+			throw InvalidArgument::create(1, '$requests', 'array|ArrayAccess&Traversable', gettype($requests));
+		}
+
+		if (is_array($options) === false) {
+			throw InvalidArgument::create(2, '$options', 'array', gettype($options));
 		}
 
 		$multihandle = curl_multi_init();
-		$subrequests = array();
-		$subhandles  = array();
+		$subrequests = [];
+		$subhandles  = [];
 
 		$class = get_class($this);
 		foreach ($requests as $id => $request) {
 			$subrequests[$id] = new $class();
 			$subhandles[$id]  = $subrequests[$id]->get_subrequest_handle($request['url'], $request['headers'], $request['data'], $request['options']);
-			$request['options']['hooks']->dispatch('curl.before_multi_add', array(&$subhandles[$id]));
+			$request['options']['hooks']->dispatch('curl.before_multi_add', [&$subhandles[$id]]);
 			curl_multi_add_handle($multihandle, $subhandles[$id]);
 		}
 
 		$completed       = 0;
-		$responses       = array();
+		$responses       = [];
 		$subrequestcount = count($subrequests);
 
-		$request['options']['hooks']->dispatch('curl.before_multi_exec', array(&$multihandle));
+		$request['options']['hooks']->dispatch('curl.before_multi_exec', [&$multihandle]);
 
 		do {
 			$active = 0;
 
 			do {
 				$status = curl_multi_exec($multihandle, $active);
-			}
-			while ($status === CURLM_CALL_MULTI_PERFORM);
+			} while ($status === CURLM_CALL_MULTI_PERFORM);
 
-			$to_process = array();
+			$to_process = [];
 
 			// Read the information as needed
 			while ($done = curl_multi_info_read($multihandle)) {
@@ -241,33 +291,32 @@ class Requests_Transport_cURL implements Requests_Transport {
 				if ($done['result'] !== CURLE_OK) {
 					//get error string for handle.
 					$reason          = curl_error($done['handle']);
-					$exception       = new Requests_Exception_Transport_cURL(
+					$exception       = new CurlException(
 						$reason,
-						Requests_Exception_Transport_cURL::EASY,
+						CurlException::EASY,
 						$done['handle'],
 						$done['result']
 					);
 					$responses[$key] = $exception;
-					$options['hooks']->dispatch('transport.internal.parse_error', array(&$responses[$key], $requests[$key]));
-				}
-				else {
+					$options['hooks']->dispatch('transport.internal.parse_error', [&$responses[$key], $requests[$key]]);
+				} else {
 					$responses[$key] = $subrequests[$key]->process_response($subrequests[$key]->response_data, $options);
 
-					$options['hooks']->dispatch('transport.internal.parse_response', array(&$responses[$key], $requests[$key]));
+					$options['hooks']->dispatch('transport.internal.parse_response', [&$responses[$key], $requests[$key]]);
 				}
 
 				curl_multi_remove_handle($multihandle, $done['handle']);
 				curl_close($done['handle']);
 
 				if (!is_string($responses[$key])) {
-					$options['hooks']->dispatch('multiple.request.complete', array(&$responses[$key], $key));
+					$options['hooks']->dispatch('multiple.request.complete', [&$responses[$key], $key]);
 				}
+
 				$completed++;
 			}
-		}
-		while ($active || $completed < $subrequestcount);
+		} while ($active || $completed < $subrequestcount);
 
-		$request['options']['hooks']->dispatch('curl.after_multi_exec', array(&$multihandle));
+		$request['options']['hooks']->dispatch('curl.after_multi_exec', [&$multihandle]);
 
 		curl_multi_close($multihandle);
 
@@ -280,8 +329,8 @@ class Requests_Transport_cURL implements Requests_Transport {
 	 * @param string $url URL to request
 	 * @param array $headers Associative array of request headers
 	 * @param string|array $data Data to send either as the POST body, or as parameters in the URL for a GET/HEAD
-	 * @param array $options Request options, see {@see Requests::response()} for documentation
-	 * @return resource Subrequest's cURL handle
+	 * @param array $options Request options, see {@see \WpOrg\Requests\Requests::response()} for documentation
+	 * @return resource|\CurlHandle Subrequest's cURL handle
 	 */
 	public function &get_subrequest_handle($url, $headers, $data, $options) {
 		$this->setup_handle($url, $headers, $data, $options);
@@ -296,6 +345,7 @@ class Requests_Transport_cURL implements Requests_Transport {
 		if ($options['max_bytes'] !== false) {
 			$this->response_byte_limit = $options['max_bytes'];
 		}
+
 		$this->hooks = $options['hooks'];
 
 		return $this->handle;
@@ -307,10 +357,10 @@ class Requests_Transport_cURL implements Requests_Transport {
 	 * @param string $url URL to request
 	 * @param array $headers Associative array of request headers
 	 * @param string|array $data Data to send either as the POST body, or as parameters in the URL for a GET/HEAD
-	 * @param array $options Request options, see {@see Requests::response()} for documentation
+	 * @param array $options Request options, see {@see \WpOrg\Requests\Requests::response()} for documentation
 	 */
-	protected function setup_handle($url, $headers, $data, $options) {
-		$options['hooks']->dispatch('curl.before_request', array(&$this->handle));
+	private function setup_handle($url, $headers, $data, $options) {
+		$options['hooks']->dispatch('curl.before_request', [&$this->handle]);
 
 		// Force closing the connection for old versions of cURL (<7.22).
 		if (!isset($headers['Connection'])) {
@@ -340,9 +390,8 @@ class Requests_Transport_cURL implements Requests_Transport {
 			if ($data_format === 'query') {
 				$url  = self::format_get($url, $data);
 				$data = '';
-			}
-			elseif (!is_string($data)) {
-				$data = http_build_query($data, null, '&');
+			} elseif (!is_string($data)) {
+				$data = http_build_query($data, '', '&');
 			}
 		}
 
@@ -379,35 +428,33 @@ class Requests_Transport_cURL implements Requests_Transport {
 
 		if (is_int($timeout) || $this->version < self::CURL_7_16_2) {
 			curl_setopt($this->handle, CURLOPT_TIMEOUT, ceil($timeout));
-		}
-		else {
+		} else {
 			// phpcs:ignore PHPCompatibility.Constants.NewConstants.curlopt_timeout_msFound
 			curl_setopt($this->handle, CURLOPT_TIMEOUT_MS, round($timeout * 1000));
 		}
 
 		if (is_int($options['connect_timeout']) || $this->version < self::CURL_7_16_2) {
 			curl_setopt($this->handle, CURLOPT_CONNECTTIMEOUT, ceil($options['connect_timeout']));
-		}
-		else {
+		} else {
 			// phpcs:ignore PHPCompatibility.Constants.NewConstants.curlopt_connecttimeout_msFound
 			curl_setopt($this->handle, CURLOPT_CONNECTTIMEOUT_MS, round($options['connect_timeout'] * 1000));
 		}
+
 		curl_setopt($this->handle, CURLOPT_URL, $url);
-		curl_setopt($this->handle, CURLOPT_REFERER, $url);
 		curl_setopt($this->handle, CURLOPT_USERAGENT, $options['useragent']);
 		if (!empty($headers)) {
 			curl_setopt($this->handle, CURLOPT_HTTPHEADER, $headers);
 		}
+
 		if ($options['protocol_version'] === 1.1) {
 			curl_setopt($this->handle, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
-		}
-		else {
+		} else {
 			curl_setopt($this->handle, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_0);
 		}
 
 		if ($options['blocking'] === true) {
-			curl_setopt($this->handle, CURLOPT_HEADERFUNCTION, array($this, 'stream_headers'));
-			curl_setopt($this->handle, CURLOPT_WRITEFUNCTION, array($this, 'stream_body'));
+			curl_setopt($this->handle, CURLOPT_HEADERFUNCTION, [$this, 'stream_headers']);
+			curl_setopt($this->handle, CURLOPT_WRITEFUNCTION, [$this, 'stream_body']);
 			curl_setopt($this->handle, CURLOPT_BUFFERSIZE, Requests::BUFFER_SIZE);
 		}
 	}
@@ -418,19 +465,19 @@ class Requests_Transport_cURL implements Requests_Transport {
 	 * @param string $response Response data from the body
 	 * @param array $options Request options
 	 * @return string|false HTTP response data including headers. False if non-blocking.
-	 * @throws Requests_Exception
+	 * @throws \WpOrg\Requests\Exception
 	 */
 	public function process_response($response, $options) {
 		if ($options['blocking'] === false) {
 			$fake_headers = '';
-			$options['hooks']->dispatch('curl.after_request', array(&$fake_headers));
+			$options['hooks']->dispatch('curl.after_request', [&$fake_headers]);
 			return false;
 		}
+
 		if ($options['filename'] !== false && $this->stream_handle) {
 			fclose($this->stream_handle);
 			$this->headers = trim($this->headers);
-		}
-		else {
+		} else {
 			$this->headers .= $response;
 		}
 
@@ -440,18 +487,19 @@ class Requests_Transport_cURL implements Requests_Transport {
 				curl_errno($this->handle),
 				curl_error($this->handle)
 			);
-			throw new Requests_Exception($error, 'curlerror', $this->handle);
+			throw new Exception($error, 'curlerror', $this->handle);
 		}
+
 		$this->info = curl_getinfo($this->handle);
 
-		$options['hooks']->dispatch('curl.after_request', array(&$this->headers, &$this->info));
+		$options['hooks']->dispatch('curl.after_request', [&$this->headers, &$this->info]);
 		return $this->headers;
 	}
 
 	/**
 	 * Collect the headers as they are received
 	 *
-	 * @param resource $handle cURL resource
+	 * @param resource|\CurlHandle $handle cURL handle
 	 * @param string $headers Header string
 	 * @return integer Length of provided header
 	 */
@@ -463,11 +511,13 @@ class Requests_Transport_cURL implements Requests_Transport {
 			$this->headers      = '';
 			$this->done_headers = false;
 		}
+
 		$this->headers .= $headers;
 
 		if ($headers === "\r\n") {
 			$this->done_headers = true;
 		}
+
 		return strlen($headers);
 	}
 
@@ -476,12 +526,12 @@ class Requests_Transport_cURL implements Requests_Transport {
 	 *
 	 * @since 1.6.1
 	 *
-	 * @param resource $handle cURL resource
+	 * @param resource|\CurlHandle $handle cURL handle
 	 * @param string $data Body data
 	 * @return integer Length of provided data
 	 */
 	public function stream_body($handle, $data) {
-		$this->hooks->dispatch('request.progress', array($data, $this->response_bytes, $this->response_byte_limit));
+		$this->hooks->dispatch('request.progress', [$data, $this->response_bytes, $this->response_byte_limit]);
 		$data_length = strlen($data);
 
 		// Are we limiting the response size?
@@ -500,8 +550,7 @@ class Requests_Transport_cURL implements Requests_Transport {
 
 		if ($this->stream_handle) {
 			fwrite($this->stream_handle, $data);
-		}
-		else {
+		} else {
 			$this->response_data .= $data;
 		}
 
@@ -513,46 +562,48 @@ class Requests_Transport_cURL implements Requests_Transport {
 	 * Format a URL given GET data
 	 *
 	 * @param string $url
-	 * @param array|object $data Data to build query using, see {@see https://secure.php.net/http_build_query}
+	 * @param array|object $data Data to build query using, see {@link https://www.php.net/http_build_query}
 	 * @return string URL with data
 	 */
-	protected static function format_get($url, $data) {
+	private static function format_get($url, $data) {
 		if (!empty($data)) {
 			$query     = '';
 			$url_parts = parse_url($url);
 			if (empty($url_parts['query'])) {
 				$url_parts['query'] = '';
-			}
-			else {
+			} else {
 				$query = $url_parts['query'];
 			}
 
-			$query .= '&' . http_build_query($data, null, '&');
+			$query .= '&' . http_build_query($data, '', '&');
 			$query  = trim($query, '&');
 
 			if (empty($url_parts['query'])) {
 				$url .= '?' . $query;
-			}
-			else {
+			} else {
 				$url = str_replace($url_parts['query'], $query, $url);
 			}
 		}
+
 		return $url;
 	}
 
 	/**
-	 * Whether this transport is valid
+	 * Self-test whether the transport can be used.
+	 *
+	 * The available capabilities to test for can be found in {@see \WpOrg\Requests\Capability}.
 	 *
 	 * @codeCoverageIgnore
-	 * @return boolean True if the transport is valid, false otherwise.
+	 * @param array<string, bool> $capabilities Optional. Associative array of capabilities to test against, i.e. `['<capability>' => true]`.
+	 * @return bool Whether the transport can be used.
 	 */
-	public static function test($capabilities = array()) {
+	public static function test($capabilities = []) {
 		if (!function_exists('curl_init') || !function_exists('curl_exec')) {
 			return false;
 		}
 
 		// If needed, check that our installed curl version supports SSL
-		if (isset($capabilities['ssl']) && $capabilities['ssl']) {
+		if (isset($capabilities[Capability::SSL]) && $capabilities[Capability::SSL]) {
 			$curl_version = curl_version();
 			if (!(CURL_VERSION_SSL & $curl_version['features'])) {
 				return false;
@@ -568,7 +619,7 @@ class Requests_Transport_cURL implements Requests_Transport {
 	 * @param string|array $data Data to send either as the POST body, or as parameters in the URL for a GET/HEAD.
 	 * @return string The "Expect" header.
 	 */
-	protected function get_expect_header($data) {
+	private function get_expect_header($data) {
 		if (!is_array($data)) {
 			return strlen((string) $data) >= 1048576 ? '100-Continue' : '';
 		}
diff --git a/wp-includes/Requests/Transport/fsockopen.php b/wp-includes/Requests/src/Transport/Fsockopen.php
similarity index 59%
rename from wp-includes/Requests/Transport/fsockopen.php
rename to wp-includes/Requests/src/Transport/Fsockopen.php
index 56f94c99f2..c3bd4a63d5 100644
--- a/wp-includes/Requests/Transport/fsockopen.php
+++ b/wp-includes/Requests/src/Transport/Fsockopen.php
@@ -2,17 +2,27 @@
 /**
  * fsockopen HTTP transport
  *
- * @package Requests
- * @subpackage Transport
+ * @package Requests\Transport
  */
 
+namespace WpOrg\Requests\Transport;
+
+use WpOrg\Requests\Capability;
+use WpOrg\Requests\Exception;
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Port;
+use WpOrg\Requests\Requests;
+use WpOrg\Requests\Ssl;
+use WpOrg\Requests\Transport;
+use WpOrg\Requests\Utility\CaseInsensitiveDictionary;
+use WpOrg\Requests\Utility\InputValidator;
+
 /**
  * fsockopen HTTP transport
  *
- * @package Requests
- * @subpackage Transport
+ * @package Requests\Transport
  */
-class Requests_Transport_fsockopen implements Requests_Transport {
+final class Fsockopen implements Transport {
 	/**
 	 * Second to microsecond conversion
 	 *
@@ -30,7 +40,7 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 	/**
 	 * Stream metadata
 	 *
-	 * @var array Associative array of properties, see {@see https://secure.php.net/stream_get_meta_data}
+	 * @var array Associative array of properties, see {@link https://www.php.net/stream_get_meta_data}
 	 */
 	public $info;
 
@@ -39,45 +49,70 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 	 *
 	 * @var int|bool Byte count, or false if no limit.
 	 */
-	protected $max_bytes = false;
+	private $max_bytes = false;
 
-	protected $connect_error = '';
+	private $connect_error = '';
 
 	/**
 	 * Perform a request
 	 *
-	 * @throws Requests_Exception On failure to connect to socket (`fsockopenerror`)
-	 * @throws Requests_Exception On socket timeout (`timeout`)
-	 *
-	 * @param string $url URL to request
+	 * @param string|Stringable $url URL to request
 	 * @param array $headers Associative array of request headers
 	 * @param string|array $data Data to send either as the POST body, or as parameters in the URL for a GET/HEAD
-	 * @param array $options Request options, see {@see Requests::response()} for documentation
+	 * @param array $options Request options, see {@see \WpOrg\Requests\Requests::response()} for documentation
 	 * @return string Raw HTTP result
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $url argument is not a string or Stringable.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $headers argument is not an array.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $data parameter is not an array or string.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $options argument is not an array.
+	 * @throws \WpOrg\Requests\Exception       On failure to connect to socket (`fsockopenerror`)
+	 * @throws \WpOrg\Requests\Exception       On socket timeout (`timeout`)
 	 */
-	public function request($url, $headers = array(), $data = array(), $options = array()) {
+	public function request($url, $headers = [], $data = [], $options = []) {
+		if (InputValidator::is_string_or_stringable($url) === false) {
+			throw InvalidArgument::create(1, '$url', 'string|Stringable', gettype($url));
+		}
+
+		if (is_array($headers) === false) {
+			throw InvalidArgument::create(2, '$headers', 'array', gettype($headers));
+		}
+
+		if (!is_array($data) && !is_string($data)) {
+			if ($data === null) {
+				$data = '';
+			} else {
+				throw InvalidArgument::create(3, '$data', 'array|string', gettype($data));
+			}
+		}
+
+		if (is_array($options) === false) {
+			throw InvalidArgument::create(4, '$options', 'array', gettype($options));
+		}
+
 		$options['hooks']->dispatch('fsockopen.before_request');
 
 		$url_parts = parse_url($url);
 		if (empty($url_parts)) {
-			throw new Requests_Exception('Invalid URL.', 'invalidurl', $url);
+			throw new Exception('Invalid URL.', 'invalidurl', $url);
 		}
+
 		$host                     = $url_parts['host'];
 		$context                  = stream_context_create();
 		$verifyname               = false;
-		$case_insensitive_headers = new Requests_Utility_CaseInsensitiveDictionary($headers);
+		$case_insensitive_headers = new CaseInsensitiveDictionary($headers);
 
 		// HTTPS support
 		if (isset($url_parts['scheme']) && strtolower($url_parts['scheme']) === 'https') {
 			$remote_socket = 'ssl://' . $host;
 			if (!isset($url_parts['port'])) {
-				$url_parts['port'] = 443;
+				$url_parts['port'] = Port::HTTPS;
 			}
 
-			$context_options = array(
+			$context_options = [
 				'verify_peer'       => true,
 				'capture_peer_cert' => true,
-			);
+			];
 			$verifyname      = true;
 
 			// SNI, if enabled (OpenSSL >=0.9.8j)
@@ -94,8 +129,7 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 					$context_options['verify_peer']      = false;
 					$context_options['verify_peer_name'] = false;
 					$verifyname                          = false;
-				}
-				elseif (is_string($options['verify'])) {
+				} elseif (is_string($options['verify'])) {
 					$context_options['cafile'] = $options['verify'];
 				}
 			}
@@ -105,39 +139,39 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 				$verifyname                          = false;
 			}
 
-			stream_context_set_option($context, array('ssl' => $context_options));
-		}
-		else {
+			stream_context_set_option($context, ['ssl' => $context_options]);
+		} else {
 			$remote_socket = 'tcp://' . $host;
 		}
 
 		$this->max_bytes = $options['max_bytes'];
 
 		if (!isset($url_parts['port'])) {
-			$url_parts['port'] = 80;
+			$url_parts['port'] = Port::HTTP;
 		}
+
 		$remote_socket .= ':' . $url_parts['port'];
 
 		// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_set_error_handler
-		set_error_handler(array($this, 'connect_error_handler'), E_WARNING | E_NOTICE);
+		set_error_handler([$this, 'connect_error_handler'], E_WARNING | E_NOTICE);
 
-		$options['hooks']->dispatch('fsockopen.remote_socket', array(&$remote_socket));
+		$options['hooks']->dispatch('fsockopen.remote_socket', [&$remote_socket]);
 
 		$socket = stream_socket_client($remote_socket, $errno, $errstr, ceil($options['connect_timeout']), STREAM_CLIENT_CONNECT, $context);
 
 		restore_error_handler();
 
 		if ($verifyname && !$this->verify_certificate_from_context($host, $context)) {
-			throw new Requests_Exception('SSL certificate did not match the requested domain name', 'ssl.no_match');
+			throw new Exception('SSL certificate did not match the requested domain name', 'ssl.no_match');
 		}
 
 		if (!$socket) {
 			if ($errno === 0) {
 				// Connection issue
-				throw new Requests_Exception(rtrim($this->connect_error), 'fsockopen.connect_error');
+				throw new Exception(rtrim($this->connect_error), 'fsockopen.connect_error');
 			}
 
-			throw new Requests_Exception($errstr, 'fsockopenerror', null, $errno);
+			throw new Exception($errstr, 'fsockopenerror', null, $errno);
 		}
 
 		$data_format = $options['data_format'];
@@ -145,12 +179,11 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 		if ($data_format === 'query') {
 			$path = self::format_get($url_parts, $data);
 			$data = '';
-		}
-		else {
-			$path = self::format_get($url_parts, array());
+		} else {
+			$path = self::format_get($url_parts, []);
 		}
 
-		$options['hooks']->dispatch('fsockopen.remote_host_path', array(&$path, $url));
+		$options['hooks']->dispatch('fsockopen.remote_host_path', [&$path, $url]);
 
 		$request_body = '';
 		$out          = sprintf("%s %s HTTP/%.1F\r\n", $options['type'], $path, $options['protocol_version']);
@@ -158,8 +191,7 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 		if ($options['type'] !== Requests::TRACE) {
 			if (is_array($data)) {
 				$request_body = http_build_query($data, '', '&');
-			}
-			else {
+			} else {
 				$request_body = $data;
 			}
 
@@ -177,11 +209,13 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 		}
 
 		if (!isset($case_insensitive_headers['Host'])) {
-			$out .= sprintf('Host: %s', $url_parts['host']);
+			$out         .= sprintf('Host: %s', $url_parts['host']);
+			$scheme_lower = strtolower($url_parts['scheme']);
 
-			if ((strtolower($url_parts['scheme']) === 'http' && $url_parts['port'] !== 80) || (strtolower($url_parts['scheme']) === 'https' && $url_parts['port'] !== 443)) {
+			if (($scheme_lower === 'http' && $url_parts['port'] !== Port::HTTP) || ($scheme_lower === 'https' && $url_parts['port'] !== Port::HTTPS)) {
 				$out .= ':' . $url_parts['port'];
 			}
+
 			$out .= "\r\n";
 		}
 
@@ -200,7 +234,7 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 			$out .= implode("\r\n", $headers) . "\r\n";
 		}
 
-		$options['hooks']->dispatch('fsockopen.after_headers', array(&$out));
+		$options['hooks']->dispatch('fsockopen.after_headers', [&$out]);
 
 		if (substr($out, -2) !== "\r\n") {
 			$out .= "\r\n";
@@ -212,25 +246,25 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 
 		$out .= "\r\n" . $request_body;
 
-		$options['hooks']->dispatch('fsockopen.before_send', array(&$out));
+		$options['hooks']->dispatch('fsockopen.before_send', [&$out]);
 
 		fwrite($socket, $out);
-		$options['hooks']->dispatch('fsockopen.after_send', array($out));
+		$options['hooks']->dispatch('fsockopen.after_send', [$out]);
 
 		if (!$options['blocking']) {
 			fclose($socket);
 			$fake_headers = '';
-			$options['hooks']->dispatch('fsockopen.after_request', array(&$fake_headers));
+			$options['hooks']->dispatch('fsockopen.after_request', [&$fake_headers]);
 			return '';
 		}
 
 		$timeout_sec = (int) floor($options['timeout']);
 		if ($timeout_sec === $options['timeout']) {
 			$timeout_msec = 0;
-		}
-		else {
+		} else {
 			$timeout_msec = self::SECOND_IN_MICROSECONDS * $options['timeout'] % self::SECOND_IN_MICROSECONDS;
 		}
+
 		stream_set_timeout($socket, $timeout_sec, $timeout_msec);
 
 		$response   = '';
@@ -241,13 +275,18 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 		$doingbody  = false;
 		$download   = false;
 		if ($options['filename']) {
-			$download = fopen($options['filename'], 'wb');
+			// phpcs:ignore WordPress.PHP.NoSilencedErrors -- Silenced the PHP native warning in favour of throwing an exception.
+			$download = @fopen($options['filename'], 'wb');
+			if ($download === false) {
+				$error = error_get_last();
+				throw new Exception($error['message'], 'fopen');
+			}
 		}
 
 		while (!feof($socket)) {
 			$this->info = stream_get_meta_data($socket);
 			if ($this->info['timed_out']) {
-				throw new Requests_Exception('fsocket timed out', 'timeout');
+				throw new Exception('fsocket timed out', 'timeout');
 			}
 
 			$block = fread($socket, Requests::BUFFER_SIZE);
@@ -261,13 +300,14 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 
 			// Are we in body mode now?
 			if ($doingbody) {
-				$options['hooks']->dispatch('request.progress', array($block, $size, $this->max_bytes));
+				$options['hooks']->dispatch('request.progress', [$block, $size, $this->max_bytes]);
 				$data_length = strlen($block);
 				if ($this->max_bytes) {
 					// Have we already hit a limit?
 					if ($size === $this->max_bytes) {
 						continue;
 					}
+
 					if (($size + $data_length) > $this->max_bytes) {
 						// Limit the length
 						$limited_length = ($this->max_bytes - $size);
@@ -278,49 +318,64 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 				$size += strlen($block);
 				if ($download) {
 					fwrite($download, $block);
-				}
-				else {
+				} else {
 					$body .= $block;
 				}
 			}
 		}
+
 		$this->headers = $headers;
 
 		if ($download) {
 			fclose($download);
-		}
-		else {
+		} else {
 			$this->headers .= "\r\n\r\n" . $body;
 		}
+
 		fclose($socket);
 
-		$options['hooks']->dispatch('fsockopen.after_request', array(&$this->headers, &$this->info));
+		$options['hooks']->dispatch('fsockopen.after_request', [&$this->headers, &$this->info]);
 		return $this->headers;
 	}
 
 	/**
 	 * Send multiple requests simultaneously
 	 *
-	 * @param array $requests Request data (array of 'url', 'headers', 'data', 'options') as per {@see Requests_Transport::request}
-	 * @param array $options Global options, see {@see Requests::response()} for documentation
-	 * @return array Array of Requests_Response objects (may contain Requests_Exception or string responses as well)
+	 * @param array $requests Request data (array of 'url', 'headers', 'data', 'options') as per {@see \WpOrg\Requests\Transport::request()}
+	 * @param array $options Global options, see {@see \WpOrg\Requests\Requests::response()} for documentation
+	 * @return array Array of \WpOrg\Requests\Response objects (may contain \WpOrg\Requests\Exception or string responses as well)
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $requests argument is not an array or iterable object with array access.
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $options argument is not an array.
 	 */
 	public function request_multiple($requests, $options) {
-		$responses = array();
+		// If you're not requesting, we can't get any responses ¯\_(ツ)_/¯
+		if (empty($requests)) {
+			return [];
+		}
+
+		if (InputValidator::has_array_access($requests) === false || InputValidator::is_iterable($requests) === false) {
+			throw InvalidArgument::create(1, '$requests', 'array|ArrayAccess&Traversable', gettype($requests));
+		}
+
+		if (is_array($options) === false) {
+			throw InvalidArgument::create(2, '$options', 'array', gettype($options));
+		}
+
+		$responses = [];
 		$class     = get_class($this);
 		foreach ($requests as $id => $request) {
 			try {
 				$handler        = new $class();
 				$responses[$id] = $handler->request($request['url'], $request['headers'], $request['data'], $request['options']);
 
-				$request['options']['hooks']->dispatch('transport.internal.parse_response', array(&$responses[$id], $request));
-			}
-			catch (Requests_Exception $e) {
+				$request['options']['hooks']->dispatch('transport.internal.parse_response', [&$responses[$id], $request]);
+			} catch (Exception $e) {
 				$responses[$id] = $e;
 			}
 
 			if (!is_string($responses[$id])) {
-				$request['options']['hooks']->dispatch('multiple.request.complete', array(&$responses[$id], $id));
+				$request['options']['hooks']->dispatch('multiple.request.complete', [&$responses[$id], $id]);
 			}
 		}
 
@@ -332,8 +387,8 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 	 *
 	 * @return string Accept-Encoding header value
 	 */
-	protected static function accept_encoding() {
-		$type = array();
+	private static function accept_encoding() {
+		$type = [];
 		if (function_exists('gzinflate')) {
 			$type[] = 'deflate;q=1.0';
 		}
@@ -351,10 +406,10 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 	 * Format a URL given GET data
 	 *
 	 * @param array $url_parts
-	 * @param array|object $data Data to build query using, see {@see https://secure.php.net/http_build_query}
+	 * @param array|object $data Data to build query using, see {@link https://www.php.net/http_build_query}
 	 * @return string URL with data
 	 */
-	protected static function format_get($url_parts, $data) {
+	private static function format_get($url_parts, $data) {
 		if (!empty($data)) {
 			if (empty($url_parts['query'])) {
 				$url_parts['query'] = '';
@@ -363,17 +418,17 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 			$url_parts['query'] .= '&' . http_build_query($data, '', '&');
 			$url_parts['query']  = trim($url_parts['query'], '&');
 		}
+
 		if (isset($url_parts['path'])) {
 			if (isset($url_parts['query'])) {
 				$get = $url_parts['path'] . '?' . $url_parts['query'];
-			}
-			else {
+			} else {
 				$get = $url_parts['path'];
 			}
-		}
-		else {
+		} else {
 			$get = '/';
 		}
+
 		return $get;
 	}
 
@@ -401,13 +456,14 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 	 * names, leading things like 'https://www.github.com/' to be invalid.
 	 * Instead
 	 *
-	 * @see https://tools.ietf.org/html/rfc2818#section-3.1 RFC2818, Section 3.1
+	 * @link https://tools.ietf.org/html/rfc2818#section-3.1 RFC2818, Section 3.1
 	 *
-	 * @throws Requests_Exception On failure to connect via TLS (`fsockopen.ssl.connect_error`)
-	 * @throws Requests_Exception On not obtaining a match for the host (`fsockopen.ssl.no_match`)
 	 * @param string $host Host name to verify against
 	 * @param resource $context Stream context
 	 * @return bool
+	 *
+	 * @throws \WpOrg\Requests\Exception On failure to connect via TLS (`fsockopen.ssl.connect_error`)
+	 * @throws \WpOrg\Requests\Exception On not obtaining a match for the host (`fsockopen.ssl.no_match`)
 	 */
 	public function verify_certificate_from_context($host, $context) {
 		$meta = stream_context_get_options($context);
@@ -415,35 +471,33 @@ class Requests_Transport_fsockopen implements Requests_Transport {
 		// If we don't have SSL options, then we couldn't make the connection at
 		// all
 		if (empty($meta) || empty($meta['ssl']) || empty($meta['ssl']['peer_certificate'])) {
-			throw new Requests_Exception(rtrim($this->connect_error), 'ssl.connect_error');
+			throw new Exception(rtrim($this->connect_error), 'ssl.connect_error');
 		}
 
 		$cert = openssl_x509_parse($meta['ssl']['peer_certificate']);
 
-		return Requests_SSL::verify_certificate($host, $cert);
+		return Ssl::verify_certificate($host, $cert);
 	}
 
 	/**
-	 * Whether this transport is valid
+	 * Self-test whether the transport can be used.
+	 *
+	 * The available capabilities to test for can be found in {@see \WpOrg\Requests\Capability}.
 	 *
 	 * @codeCoverageIgnore
-	 * @return boolean True if the transport is valid, false otherwise.
+	 * @param array<string, bool> $capabilities Optional. Associative array of capabilities to test against, i.e. `['<capability>' => true]`.
+	 * @return bool Whether the transport can be used.
 	 */
-	public static function test($capabilities = array()) {
+	public static function test($capabilities = []) {
 		if (!function_exists('fsockopen')) {
 			return false;
 		}
 
 		// If needed, check that streams support SSL
-		if (isset($capabilities['ssl']) && $capabilities['ssl']) {
+		if (isset($capabilities[Capability::SSL]) && $capabilities[Capability::SSL]) {
 			if (!extension_loaded('openssl') || !function_exists('openssl_x509_parse')) {
 				return false;
 			}
-
-			// Currently broken, thanks to https://github.com/facebook/hhvm/issues/2156
-			if (defined('HHVM_VERSION')) {
-				return false;
-			}
 		}
 
 		return true;
diff --git a/wp-includes/Requests/src/Utility/CaseInsensitiveDictionary.php b/wp-includes/Requests/src/Utility/CaseInsensitiveDictionary.php
new file mode 100644
index 0000000000..3c24cebd4f
--- /dev/null
+++ b/wp-includes/Requests/src/Utility/CaseInsensitiveDictionary.php
@@ -0,0 +1,127 @@
+<?php
+/**
+ * Case-insensitive dictionary, suitable for HTTP headers
+ *
+ * @package Requests\Utilities
+ */
+
+namespace WpOrg\Requests\Utility;
+
+use ArrayAccess;
+use ArrayIterator;
+use IteratorAggregate;
+use ReturnTypeWillChange;
+use WpOrg\Requests\Exception;
+
+/**
+ * Case-insensitive dictionary, suitable for HTTP headers
+ *
+ * @package Requests\Utilities
+ */
+class CaseInsensitiveDictionary implements ArrayAccess, IteratorAggregate {
+	/**
+	 * Actual item data
+	 *
+	 * @var array
+	 */
+	protected $data = [];
+
+	/**
+	 * Creates a case insensitive dictionary.
+	 *
+	 * @param array $data Dictionary/map to convert to case-insensitive
+	 */
+	public function __construct(array $data = []) {
+		foreach ($data as $offset => $value) {
+			$this->offsetSet($offset, $value);
+		}
+	}
+
+	/**
+	 * Check if the given item exists
+	 *
+	 * @param string $offset Item key
+	 * @return boolean Does the item exist?
+	 */
+	#[ReturnTypeWillChange]
+	public function offsetExists($offset) {
+		if (is_string($offset)) {
+			$offset = strtolower($offset);
+		}
+
+		return isset($this->data[$offset]);
+	}
+
+	/**
+	 * Get the value for the item
+	 *
+	 * @param string $offset Item key
+	 * @return string|null Item value (null if the item key doesn't exist)
+	 */
+	#[ReturnTypeWillChange]
+	public function offsetGet($offset) {
+		if (is_string($offset)) {
+			$offset = strtolower($offset);
+		}
+
+		if (!isset($this->data[$offset])) {
+			return null;
+		}
+
+		return $this->data[$offset];
+	}
+
+	/**
+	 * Set the given item
+	 *
+	 * @param string $offset Item name
+	 * @param string $value Item value
+	 *
+	 * @throws \WpOrg\Requests\Exception On attempting to use dictionary as list (`invalidset`)
+	 */
+	#[ReturnTypeWillChange]
+	public function offsetSet($offset, $value) {
+		if ($offset === null) {
+			throw new Exception('Object is a dictionary, not a list', 'invalidset');
+		}
+
+		if (is_string($offset)) {
+			$offset = strtolower($offset);
+		}
+
+		$this->data[$offset] = $value;
+	}
+
+	/**
+	 * Unset the given header
+	 *
+	 * @param string $offset
+	 */
+	#[ReturnTypeWillChange]
+	public function offsetUnset($offset) {
+		if (is_string($offset)) {
+			$offset = strtolower($offset);
+		}
+
+		unset($this->data[$offset]);
+	}
+
+	/**
+	 * Get an iterator for the data
+	 *
+	 * @return \ArrayIterator
+	 */
+	#[ReturnTypeWillChange]
+	public function getIterator() {
+		return new ArrayIterator($this->data);
+	}
+
+	/**
+	 * Get the headers as an array
+	 *
+	 * @return array Header data
+	 */
+	public function getAll() {
+		return $this->data;
+	}
+}
diff --git a/wp-includes/Requests/src/Utility/FilteredIterator.php b/wp-includes/Requests/src/Utility/FilteredIterator.php
new file mode 100644
index 0000000000..973a5d25a5
--- /dev/null
+++ b/wp-includes/Requests/src/Utility/FilteredIterator.php
@@ -0,0 +1,82 @@
+<?php
+/**
+ * Iterator for arrays requiring filtered values
+ *
+ * @package Requests\Utilities
+ */
+
+namespace WpOrg\Requests\Utility;
+
+use ArrayIterator;
+use ReturnTypeWillChange;
+use WpOrg\Requests\Exception\InvalidArgument;
+use WpOrg\Requests\Utility\InputValidator;
+
+/**
+ * Iterator for arrays requiring filtered values
+ *
+ * @package Requests\Utilities
+ */
+final class FilteredIterator extends ArrayIterator {
+	/**
+	 * Callback to run as a filter
+	 *
+	 * @var callable
+	 */
+	private $callback;
+
+	/**
+	 * Create a new iterator
+	 *
+	 * @param array $data
+	 * @param callable $callback Callback to be called on each value
+	 *
+	 * @throws \WpOrg\Requests\Exception\InvalidArgument When the passed $data argument is not iterable.
+	 */
+	public function __construct($data, $callback) {
+		if (InputValidator::is_iterable($data) === false) {
+			throw InvalidArgument::create(1, '$data', 'iterable', gettype($data));
+		}
+
+		parent::__construct($data);
+
+		if (is_callable($callback)) {
+			$this->callback = $callback;
+		}
+	}
+
+	/**
+	 * @inheritdoc
+	 *
+	 * @phpcs:disable PHPCompatibility.FunctionNameRestrictions.NewMagicMethods.__unserializeFound
+	 */
+	#[ReturnTypeWillChange]
+	public function __unserialize($data) {}
+	// phpcs:enable
+
+	public function __wakeup() {
+		unset($this->callback);
+	}
+
+	/**
+	 * Get the current item's value after filtering
+	 *
+	 * @return string
+	 */
+	#[ReturnTypeWillChange]
+	public function current() {
+		$value = parent::current();
+
+		if (is_callable($this->callback)) {
+			$value = call_user_func($this->callback, $value);
+		}
+
+		return $value;
+	}
+
+	/**
+	 * @inheritdoc
+	 */
+	#[ReturnTypeWillChange]
+	public function unserialize($data) {}
+}
diff --git a/wp-includes/Requests/src/Utility/InputValidator.php b/wp-includes/Requests/src/Utility/InputValidator.php
new file mode 100644
index 0000000000..7c10d61a4b
--- /dev/null
+++ b/wp-includes/Requests/src/Utility/InputValidator.php
@@ -0,0 +1,109 @@
+<?php
+/**
+ * Input validation utilities.
+ *
+ * @package Requests\Utilities
+ */
+
+namespace WpOrg\Requests\Utility;
+
+use ArrayAccess;
+use CurlHandle;
+use Traversable;
+
+/**
+ * Input validation utilities.
+ *
+ * @package Requests\Utilities
+ */
+final class InputValidator {
+
+	/**
+	 * Verify that a received input parameter is of type string or is "stringable".
+	 *
+	 * @param mixed $input Input parameter to verify.
+	 *
+	 * @return bool
+	 */
+	public static function is_string_or_stringable($input) {
+		return is_string($input) || self::is_stringable_object($input);
+	}
+
+	/**
+	 * Verify whether a received input parameter is usable as an integer array key.
+	 *
+	 * @param mixed $input Input parameter to verify.
+	 *
+	 * @return bool
+	 */
+	public static function is_numeric_array_key($input) {
+		if (is_int($input)) {
+			return true;
+		}
+
+		if (!is_string($input)) {
+			return false;
+		}
+
+		return (bool) preg_match('`^-?[0-9]+$`', $input);
+	}
+
+	/**
+	 * Verify whether a received input parameter is "stringable".
+	 *
+	 * @param mixed $input Input parameter to verify.
+	 *
+	 * @return bool
+	 */
+	public static function is_stringable_object($input) {
+		return is_object($input) && method_exists($input, '__toString');
+	}
+
+	/**
+	 * Verify whether a received input parameter is _accessible as if it were an array_.
+	 *
+	 * @param mixed $input Input parameter to verify.
+	 *
+	 * @return bool
+	 */
+	public static function has_array_access($input) {
+		return is_array($input) || $input instanceof ArrayAccess;
+	}
+
+	/**
+	 * Verify whether a received input parameter is "iterable".
+	 *
+	 * @internal The PHP native `is_iterable()` function was only introduced in PHP 7.1
+	 * and this library still supports PHP 5.6.
+	 *
+	 * @param mixed $input Input parameter to verify.
+	 *
+	 * @return bool
+	 */
+	public static function is_iterable($input) {
+		return is_array($input) || $input instanceof Traversable;
+	}
+
+	/**
+	 * Verify whether a received input parameter is a Curl handle.
+	 *
+	 * The PHP Curl extension worked with resources prior to PHP 8.0 and with
+	 * an instance of the `CurlHandle` class since PHP 8.0.
+	 * {@link https://www.php.net/manual/en/migration80.incompatible.php#migration80.incompatible.resource2object}
+	 *
+	 * @param mixed $input Input parameter to verify.
+	 *
+	 * @return bool
+	 */
+	public static function is_curl_handle($input) {
+		if (is_resource($input)) {
+			return get_resource_type($input) === 'curl';
+		}
+
+		if (is_object($input)) {
+			return $input instanceof CurlHandle;
+		}
+
+		return false;
+	}
+}
diff --git a/wp-includes/class-requests.php b/wp-includes/class-requests.php
index 31bbbefe11..47ef04ff62 100644
--- a/wp-includes/class-requests.php
+++ b/wp-includes/class-requests.php
@@ -7,8 +7,31 @@
  * Based on concepts from SimplePie_File, RequestCore and WP_Http.
  *
  * @package Requests
+ *
+ * @deprecated 6.2.0
  */
 
+/*
+ * Integrators who cannot yet upgrade to the PSR-4 class names can silence deprecations
+ * by defining a `REQUESTS_SILENCE_PSR0_DEPRECATIONS` constant and setting it to `true`.
+ * The constant needs to be defined before this class is required.
+ */
+if (!defined('REQUESTS_SILENCE_PSR0_DEPRECATIONS') || REQUESTS_SILENCE_PSR0_DEPRECATIONS !== true) {
+	// phpcs:ignore WordPress.PHP.DevelopmentFunctions.error_log_trigger_error
+	trigger_error(
+		'The PSR-0 `Requests_...` class names in the Request library are deprecated.'
+		. ' Switch to the PSR-4 `WpOrg\Requests\...` class names at your earliest convenience.',
+		E_USER_DEPRECATED
+	);
+
+	// Prevent the deprecation notice from being thrown twice.
+	if (!defined('REQUESTS_SILENCE_PSR0_DEPRECATIONS')) {
+		define('REQUESTS_SILENCE_PSR0_DEPRECATIONS', true);
+	}
+}
+
+require_once __DIR__ . '/Requests/src/Requests.php';
+
 /**
  * Requests for PHP
  *
@@ -17,985 +40,39 @@
  * Based on concepts from SimplePie_File, RequestCore and WP_Http.
  *
  * @package Requests
+ *
+ * @deprecated 6.2.0 Use `WpOrg\Requests\Requests` instead for the actual functionality and
+ *                   use `WpOrg\Requests\Autoload` for the autoloading.
  */
-class Requests {
-	/**
-	 * POST method
-	 *
-	 * @var string
-	 */
-	const POST = 'POST';
+class Requests extends WpOrg\Requests\Requests {
 
 	/**
-	 * PUT method
+	 * Deprecated autoloader for Requests.
 	 *
-	 * @var string
-	 */
-	const PUT = 'PUT';
-
-	/**
-	 * GET method
-	 *
-	 * @var string
-	 */
-	const GET = 'GET';
-
-	/**
-	 * HEAD method
-	 *
-	 * @var string
-	 */
-	const HEAD = 'HEAD';
-
-	/**
-	 * DELETE method
-	 *
-	 * @var string
-	 */
-	const DELETE = 'DELETE';
-
-	/**
-	 * OPTIONS method
-	 *
-	 * @var string
-	 */
-	const OPTIONS = 'OPTIONS';
-
-	/**
-	 * TRACE method
-	 *
-	 * @var string
-	 */
-	const TRACE = 'TRACE';
-
-	/**
-	 * PATCH method
-	 *
-	 * @link https://tools.ietf.org/html/rfc5789
-	 * @var string
-	 */
-	const PATCH = 'PATCH';
-
-	/**
-	 * Default size of buffer size to read streams
-	 *
-	 * @var integer
-	 */
-	const BUFFER_SIZE = 1160;
-
-	/**
-	 * Current version of Requests
-	 *
-	 * @var string
-	 */
-	const VERSION = '1.8.1';
-
-	/**
-	 * Registered transport classes
-	 *
-	 * @var array
-	 */
-	protected static $transports = array();
-
-	/**
-	 * Selected transport name
-	 *
-	 * Use {@see get_transport()} instead
-	 *
-	 * @var array
-	 */
-	public static $transport = array();
-
-	/**
-	 * Default certificate path.
-	 *
-	 * @see Requests::get_certificate_path()
-	 * @see Requests::set_certificate_path()
-	 *
-	 * @var string
-	 */
-	protected static $certificate_path;
-
-	/**
-	 * This is a static class, do not instantiate it
-	 *
-	 * @codeCoverageIgnore
-	 */
-	private function __construct() {}
-
-	/**
-	 * Autoloader for Requests
-	 *
-	 * Register this with {@see register_autoloader()} if you'd like to avoid
-	 * having to create your own.
-	 *
-	 * (You can also use `spl_autoload_register` directly if you'd prefer.)
+	 * @deprecated 6.2.0 Use the `WpOrg\Requests\Autoload::load()` method instead.
 	 *
 	 * @codeCoverageIgnore
 	 *
 	 * @param string $class Class name to load
 	 */
 	public static function autoloader($class) {
-		// Check that the class starts with "Requests"
-		if (strpos($class, 'Requests') !== 0) {
-			return;
+		if (class_exists('WpOrg\Requests\Autoload') === false) {
+			require_once __DIR__ . '/Requests/src/Autoload.php';
 		}
 
-		$file = str_replace('_', '/', $class);
-		if (file_exists(dirname(__FILE__) . '/' . $file . '.php')) {
-			require_once dirname(__FILE__) . '/' . $file . '.php';
-		}
+		return WpOrg\Requests\Autoload::load($class);
 	}
 
 	/**
 	 * Register the built-in autoloader
 	 *
+	 * @deprecated 6.2.0 Include the `WpOrg\Requests\Autoload` class and
+	 *                   call `WpOrg\Requests\Autoload::register()` instead.
+	 *
 	 * @codeCoverageIgnore
 	 */
 	public static function register_autoloader() {
-		spl_autoload_register(array('Requests', 'autoloader'));
-	}
-
-	/**
-	 * Register a transport
-	 *
-	 * @param string $transport Transport class to add, must support the Requests_Transport interface
-	 */
-	public static function add_transport($transport) {
-		if (empty(self::$transports)) {
-			self::$transports = array(
-				'Requests_Transport_cURL',
-				'Requests_Transport_fsockopen',
-			);
-		}
-
-		self::$transports = array_merge(self::$transports, array($transport));
-	}
-
-	/**
-	 * Get a working transport
-	 *
-	 * @throws Requests_Exception If no valid transport is found (`notransport`)
-	 * @return Requests_Transport
-	 */
-	protected static function get_transport($capabilities = array()) {
-		// Caching code, don't bother testing coverage
-		// @codeCoverageIgnoreStart
-		// array of capabilities as a string to be used as an array key
-		ksort($capabilities);
-		$cap_string = serialize($capabilities);
-
-		// Don't search for a transport if it's already been done for these $capabilities
-		if (isset(self::$transport[$cap_string]) && self::$transport[$cap_string] !== null) {
-			$class = self::$transport[$cap_string];
-			return new $class();
-		}
-		// @codeCoverageIgnoreEnd
-
-		if (empty(self::$transports)) {
-			self::$transports = array(
-				'Requests_Transport_cURL',
-				'Requests_Transport_fsockopen',
-			);
-		}
-
-		// Find us a working transport
-		foreach (self::$transports as $class) {
-			if (!class_exists($class)) {
-				continue;
-			}
-
-			$result = call_user_func(array($class, 'test'), $capabilities);
-			if ($result) {
-				self::$transport[$cap_string] = $class;
-				break;
-			}
-		}
-		if (self::$transport[$cap_string] === null) {
-			throw new Requests_Exception('No working transports found', 'notransport', self::$transports);
-		}
-
-		$class = self::$transport[$cap_string];
-		return new $class();
-	}
-
-	/**#@+
-	 * @see request()
-	 * @param string $url
-	 * @param array $headers
-	 * @param array $options
-	 * @return Requests_Response
-	 */
-	/**
-	 * Send a GET request
-	 */
-	public static function get($url, $headers = array(), $options = array()) {
-		return self::request($url, $headers, null, self::GET, $options);
-	}
-
-	/**
-	 * Send a HEAD request
-	 */
-	public static function head($url, $headers = array(), $options = array()) {
-		return self::request($url, $headers, null, self::HEAD, $options);
-	}
-
-	/**
-	 * Send a DELETE request
-	 */
-	public static function delete($url, $headers = array(), $options = array()) {
-		return self::request($url, $headers, null, self::DELETE, $options);
-	}
-
-	/**
-	 * Send a TRACE request
-	 */
-	public static function trace($url, $headers = array(), $options = array()) {
-		return self::request($url, $headers, null, self::TRACE, $options);
-	}
-	/**#@-*/
-
-	/**#@+
-	 * @see request()
-	 * @param string $url
-	 * @param array $headers
-	 * @param array $data
-	 * @param array $options
-	 * @return Requests_Response
-	 */
-	/**
-	 * Send a POST request
-	 */
-	public static function post($url, $headers = array(), $data = array(), $options = array()) {
-		return self::request($url, $headers, $data, self::POST, $options);
-	}
-	/**
-	 * Send a PUT request
-	 */
-	public static function put($url, $headers = array(), $data = array(), $options = array()) {
-		return self::request($url, $headers, $data, self::PUT, $options);
-	}
-
-	/**
-	 * Send an OPTIONS request
-	 */
-	public static function options($url, $headers = array(), $data = array(), $options = array()) {
-		return self::request($url, $headers, $data, self::OPTIONS, $options);
-	}
-
-	/**
-	 * Send a PATCH request
-	 *
-	 * Note: Unlike {@see post} and {@see put}, `$headers` is required, as the
-	 * specification recommends that should send an ETag
-	 *
-	 * @link https://tools.ietf.org/html/rfc5789
-	 */
-	public static function patch($url, $headers, $data = array(), $options = array()) {
-		return self::request($url, $headers, $data, self::PATCH, $options);
-	}
-	/**#@-*/
-
-	/**
-	 * Main interface for HTTP requests
-	 *
-	 * This method initiates a request and sends it via a transport before
-	 * parsing.
-	 *
-	 * The `$options` parameter takes an associative array with the following
-	 * options:
-	 *
-	 * - `timeout`: How long should we wait for a response?
-	 *    Note: for cURL, a minimum of 1 second applies, as DNS resolution
-	 *    operates at second-resolution only.
-	 *    (float, seconds with a millisecond precision, default: 10, example: 0.01)
-	 * - `connect_timeout`: How long should we wait while trying to connect?
-	 *    (float, seconds with a millisecond precision, default: 10, example: 0.01)
-	 * - `useragent`: Useragent to send to the server
-	 *    (string, default: php-requests/$version)
-	 * - `follow_redirects`: Should we follow 3xx redirects?
-	 *    (boolean, default: true)
-	 * - `redirects`: How many times should we redirect before erroring?
-	 *    (integer, default: 10)
-	 * - `blocking`: Should we block processing on this request?
-	 *    (boolean, default: true)
-	 * - `filename`: File to stream the body to instead.
-	 *    (string|boolean, default: false)
-	 * - `auth`: Authentication handler or array of user/password details to use
-	 *    for Basic authentication
-	 *    (Requests_Auth|array|boolean, default: false)
-	 * - `proxy`: Proxy details to use for proxy by-passing and authentication
-	 *    (Requests_Proxy|array|string|boolean, default: false)
-	 * - `max_bytes`: Limit for the response body size.
-	 *    (integer|boolean, default: false)
-	 * - `idn`: Enable IDN parsing
-	 *    (boolean, default: true)
-	 * - `transport`: Custom transport. Either a class name, or a
-	 *    transport object. Defaults to the first working transport from
-	 *    {@see getTransport()}
-	 *    (string|Requests_Transport, default: {@see getTransport()})
-	 * - `hooks`: Hooks handler.
-	 *    (Requests_Hooker, default: new Requests_Hooks())
-	 * - `verify`: Should we verify SSL certificates? Allows passing in a custom
-	 *    certificate file as a string. (Using true uses the system-wide root
-	 *    certificate store instead, but this may have different behaviour
-	 *    across transports.)
-	 *    (string|boolean, default: library/Requests/Transport/cacert.pem)
-	 * - `verifyname`: Should we verify the common name in the SSL certificate?
-	 *    (boolean, default: true)
-	 * - `data_format`: How should we send the `$data` parameter?
-	 *    (string, one of 'query' or 'body', default: 'query' for
-	 *    HEAD/GET/DELETE, 'body' for POST/PUT/OPTIONS/PATCH)
-	 *
-	 * @throws Requests_Exception On invalid URLs (`nonhttp`)
-	 *
-	 * @param string $url URL to request
-	 * @param array $headers Extra headers to send with the request
-	 * @param array|null $data Data to send either as a query string for GET/HEAD requests, or in the body for POST requests
-	 * @param string $type HTTP request type (use Requests constants)
-	 * @param array $options Options for the request (see description for more information)
-	 * @return Requests_Response
-	 */
-	public static function request($url, $headers = array(), $data = array(), $type = self::GET, $options = array()) {
-		if (empty($options['type'])) {
-			$options['type'] = $type;
-		}
-		$options = array_merge(self::get_default_options(), $options);
-
-		self::set_defaults($url, $headers, $data, $type, $options);
-
-		$options['hooks']->dispatch('requests.before_request', array(&$url, &$headers, &$data, &$type, &$options));
-
-		if (!empty($options['transport'])) {
-			$transport = $options['transport'];
-
-			if (is_string($options['transport'])) {
-				$transport = new $transport();
-			}
-		}
-		else {
-			$need_ssl     = (stripos($url, 'https://') === 0);
-			$capabilities = array('ssl' => $need_ssl);
-			$transport    = self::get_transport($capabilities);
-		}
-		$response = $transport->request($url, $headers, $data, $options);
-
-		$options['hooks']->dispatch('requests.before_parse', array(&$response, $url, $headers, $data, $type, $options));
-
-		return self::parse_response($response, $url, $headers, $data, $options);
-	}
-
-	/**
-	 * Send multiple HTTP requests simultaneously
-	 *
-	 * The `$requests` parameter takes an associative or indexed array of
-	 * request fields. The key of each request can be used to match up the
-	 * request with the returned data, or with the request passed into your
-	 * `multiple.request.complete` callback.
-	 *
-	 * The request fields value is an associative array with the following keys:
-	 *
-	 * - `url`: Request URL Same as the `$url` parameter to
-	 *    {@see Requests::request}
-	 *    (string, required)
-	 * - `headers`: Associative array of header fields. Same as the `$headers`
-	 *    parameter to {@see Requests::request}
-	 *    (array, default: `array()`)
-	 * - `data`: Associative array of data fields or a string. Same as the
-	 *    `$data` parameter to {@see Requests::request}
-	 *    (array|string, default: `array()`)
-	 * - `type`: HTTP request type (use Requests constants). Same as the `$type`
-	 *    parameter to {@see Requests::request}
-	 *    (string, default: `Requests::GET`)
-	 * - `cookies`: Associative array of cookie name to value, or cookie jar.
-	 *    (array|Requests_Cookie_Jar)
-	 *
-	 * If the `$options` parameter is specified, individual requests will
-	 * inherit options from it. This can be used to use a single hooking system,
-	 * or set all the types to `Requests::POST`, for example.
-	 *
-	 * In addition, the `$options` parameter takes the following global options:
-	 *
-	 * - `complete`: A callback for when a request is complete. Takes two
-	 *    parameters, a Requests_Response/Requests_Exception reference, and the
-	 *    ID from the request array (Note: this can also be overridden on a
-	 *    per-request basis, although that's a little silly)
-	 *    (callback)
-	 *
-	 * @param array $requests Requests data (see description for more information)
-	 * @param array $options Global and default options (see {@see Requests::request})
-	 * @return array Responses (either Requests_Response or a Requests_Exception object)
-	 */
-	public static function request_multiple($requests, $options = array()) {
-		$options = array_merge(self::get_default_options(true), $options);
-
-		if (!empty($options['hooks'])) {
-			$options['hooks']->register('transport.internal.parse_response', array('Requests', 'parse_multiple'));
-			if (!empty($options['complete'])) {
-				$options['hooks']->register('multiple.request.complete', $options['complete']);
-			}
-		}
-
-		foreach ($requests as $id => &$request) {
-			if (!isset($request['headers'])) {
-				$request['headers'] = array();
-			}
-			if (!isset($request['data'])) {
-				$request['data'] = array();
-			}
-			if (!isset($request['type'])) {
-				$request['type'] = self::GET;
-			}
-			if (!isset($request['options'])) {
-				$request['options']         = $options;
-				$request['options']['type'] = $request['type'];
-			}
-			else {
-				if (empty($request['options']['type'])) {
-					$request['options']['type'] = $request['type'];
-				}
-				$request['options'] = array_merge($options, $request['options']);
-			}
-
-			self::set_defaults($request['url'], $request['headers'], $request['data'], $request['type'], $request['options']);
-
-			// Ensure we only hook in once
-			if ($request['options']['hooks'] !== $options['hooks']) {
-				$request['options']['hooks']->register('transport.internal.parse_response', array('Requests', 'parse_multiple'));
-				if (!empty($request['options']['complete'])) {
-					$request['options']['hooks']->register('multiple.request.complete', $request['options']['complete']);
-				}
-			}
-		}
-		unset($request);
-
-		if (!empty($options['transport'])) {
-			$transport = $options['transport'];
-
-			if (is_string($options['transport'])) {
-				$transport = new $transport();
-			}
-		}
-		else {
-			$transport = self::get_transport();
-		}
-		$responses = $transport->request_multiple($requests, $options);
-
-		foreach ($responses as $id => &$response) {
-			// If our hook got messed with somehow, ensure we end up with the
-			// correct response
-			if (is_string($response)) {
-				$request = $requests[$id];
-				self::parse_multiple($response, $request);
-				$request['options']['hooks']->dispatch('multiple.request.complete', array(&$response, $id));
-			}
-		}
-
-		return $responses;
-	}
-
-	/**
-	 * Get the default options
-	 *
-	 * @see Requests::request() for values returned by this method
-	 * @param boolean $multirequest Is this a multirequest?
-	 * @return array Default option values
-	 */
-	protected static function get_default_options($multirequest = false) {
-		$defaults = array(
-			'timeout'          => 10,
-			'connect_timeout'  => 10,
-			'useragent'        => 'php-requests/' . self::VERSION,
-			'protocol_version' => 1.1,
-			'redirected'       => 0,
-			'redirects'        => 10,
-			'follow_redirects' => true,
-			'blocking'         => true,
-			'type'             => self::GET,
-			'filename'         => false,
-			'auth'             => false,
-			'proxy'            => false,
-			'cookies'          => false,
-			'max_bytes'        => false,
-			'idn'              => true,
-			'hooks'            => null,
-			'transport'        => null,
-			'verify'           => self::get_certificate_path(),
-			'verifyname'       => true,
-		);
-		if ($multirequest !== false) {
-			$defaults['complete'] = null;
-		}
-		return $defaults;
-	}
-
-	/**
-	 * Get default certificate path.
-	 *
-	 * @return string Default certificate path.
-	 */
-	public static function get_certificate_path() {
-		if (!empty(self::$certificate_path)) {
-			return self::$certificate_path;
-		}
-
-		return dirname(__FILE__) . '/Requests/Transport/cacert.pem';
-	}
-
-	/**
-	 * Set default certificate path.
-	 *
-	 * @param string $path Certificate path, pointing to a PEM file.
-	 */
-	public static function set_certificate_path($path) {
-		self::$certificate_path = $path;
-	}
-
-	/**
-	 * Set the default values
-	 *
-	 * @param string $url URL to request
-	 * @param array $headers Extra headers to send with the request
-	 * @param array|null $data Data to send either as a query string for GET/HEAD requests, or in the body for POST requests
-	 * @param string $type HTTP request type
-	 * @param array $options Options for the request
-	 * @return array $options
-	 */
-	protected static function set_defaults(&$url, &$headers, &$data, &$type, &$options) {
-		if (!preg_match('/^http(s)?:\/\//i', $url, $matches)) {
-			throw new Requests_Exception('Only HTTP(S) requests are handled.', 'nonhttp', $url);
-		}
-
-		if (empty($options['hooks'])) {
-			$options['hooks'] = new Requests_Hooks();
-		}
-
-		if (is_array($options['auth'])) {
-			$options['auth'] = new Requests_Auth_Basic($options['auth']);
-		}
-		if ($options['auth'] !== false) {
-			$options['auth']->register($options['hooks']);
-		}
-
-		if (is_string($options['proxy']) || is_array($options['proxy'])) {
-			$options['proxy'] = new Requests_Proxy_HTTP($options['proxy']);
-		}
-		if ($options['proxy'] !== false) {
-			$options['proxy']->register($options['hooks']);
-		}
-
-		if (is_array($options['cookies'])) {
-			$options['cookies'] = new Requests_Cookie_Jar($options['cookies']);
-		}
-		elseif (empty($options['cookies'])) {
-			$options['cookies'] = new Requests_Cookie_Jar();
-		}
-		if ($options['cookies'] !== false) {
-			$options['cookies']->register($options['hooks']);
-		}
-
-		if ($options['idn'] !== false) {
-			$iri       = new Requests_IRI($url);
-			$iri->host = Requests_IDNAEncoder::encode($iri->ihost);
-			$url       = $iri->uri;
-		}
-
-		// Massage the type to ensure we support it.
-		$type = strtoupper($type);
-
-		if (!isset($options['data_format'])) {
-			if (in_array($type, array(self::HEAD, self::GET, self::DELETE), true)) {
-				$options['data_format'] = 'query';
-			}
-			else {
-				$options['data_format'] = 'body';
-			}
-		}
-	}
-
-	/**
-	 * HTTP response parser
-	 *
-	 * @throws Requests_Exception On missing head/body separator (`requests.no_crlf_separator`)
-	 * @throws Requests_Exception On missing head/body separator (`noversion`)
-	 * @throws Requests_Exception On missing head/body separator (`toomanyredirects`)
-	 *
-	 * @param string $headers Full response text including headers and body
-	 * @param string $url Original request URL
-	 * @param array $req_headers Original $headers array passed to {@link request()}, in case we need to follow redirects
-	 * @param array $req_data Original $data array passed to {@link request()}, in case we need to follow redirects
-	 * @param array $options Original $options array passed to {@link request()}, in case we need to follow redirects
-	 * @return Requests_Response
-	 */
-	protected static function parse_response($headers, $url, $req_headers, $req_data, $options) {
-		$return = new Requests_Response();
-		if (!$options['blocking']) {
-			return $return;
-		}
-
-		$return->raw  = $headers;
-		$return->url  = (string) $url;
-		$return->body = '';
-
-		if (!$options['filename']) {
-			$pos = strpos($headers, "\r\n\r\n");
-			if ($pos === false) {
-				// Crap!
-				throw new Requests_Exception('Missing header/body separator', 'requests.no_crlf_separator');
-			}
-
-			$headers = substr($return->raw, 0, $pos);
-			// Headers will always be separated from the body by two new lines - `\n\r\n\r`.
-			$body = substr($return->raw, $pos + 4);
-			if (!empty($body)) {
-				$return->body = $body;
-			}
-		}
-		// Pretend CRLF = LF for compatibility (RFC 2616, section 19.3)
-		$headers = str_replace("\r\n", "\n", $headers);
-		// Unfold headers (replace [CRLF] 1*( SP | HT ) with SP) as per RFC 2616 (section 2.2)
-		$headers = preg_replace('/\n[ \t]/', ' ', $headers);
-		$headers = explode("\n", $headers);
-		preg_match('#^HTTP/(1\.\d)[ \t]+(\d+)#i', array_shift($headers), $matches);
-		if (empty($matches)) {
-			throw new Requests_Exception('Response could not be parsed', 'noversion', $headers);
-		}
-		$return->protocol_version = (float) $matches[1];
-		$return->status_code      = (int) $matches[2];
-		if ($return->status_code >= 200 && $return->status_code < 300) {
-			$return->success = true;
-		}
-
-		foreach ($headers as $header) {
-			list($key, $value) = explode(':', $header, 2);
-			$value             = trim($value);
-			preg_replace('#(\s+)#i', ' ', $value);
-			$return->headers[$key] = $value;
-		}
-		if (isset($return->headers['transfer-encoding'])) {
-			$return->body = self::decode_chunked($return->body);
-			unset($return->headers['transfer-encoding']);
-		}
-		if (isset($return->headers['content-encoding'])) {
-			$return->body = self::decompress($return->body);
-		}
-
-		//fsockopen and cURL compatibility
-		if (isset($return->headers['connection'])) {
-			unset($return->headers['connection']);
-		}
-
-		$options['hooks']->dispatch('requests.before_redirect_check', array(&$return, $req_headers, $req_data, $options));
-
-		if ($return->is_redirect() && $options['follow_redirects'] === true) {
-			if (isset($return->headers['location']) && $options['redirected'] < $options['redirects']) {
-				if ($return->status_code === 303) {
-					$options['type'] = self::GET;
-				}
-				$options['redirected']++;
-				$location = $return->headers['location'];
-				if (strpos($location, 'http://') !== 0 && strpos($location, 'https://') !== 0) {
-					// relative redirect, for compatibility make it absolute
-					$location = Requests_IRI::absolutize($url, $location);
-					$location = $location->uri;
-				}
-
-				$hook_args = array(
-					&$location,
-					&$req_headers,
-					&$req_data,
-					&$options,
-					$return,
-				);
-				$options['hooks']->dispatch('requests.before_redirect', $hook_args);
-				$redirected            = self::request($location, $req_headers, $req_data, $options['type'], $options);
-				$redirected->history[] = $return;
-				return $redirected;
-			}
-			elseif ($options['redirected'] >= $options['redirects']) {
-				throw new Requests_Exception('Too many redirects', 'toomanyredirects', $return);
-			}
-		}
-
-		$return->redirects = $options['redirected'];
-
-		$options['hooks']->dispatch('requests.after_request', array(&$return, $req_headers, $req_data, $options));
-		return $return;
-	}
-
-	/**
-	 * Callback for `transport.internal.parse_response`
-	 *
-	 * Internal use only. Converts a raw HTTP response to a Requests_Response
-	 * while still executing a multiple request.
-	 *
-	 * @param string $response Full response text including headers and body (will be overwritten with Response instance)
-	 * @param array $request Request data as passed into {@see Requests::request_multiple()}
-	 * @return null `$response` is either set to a Requests_Response instance, or a Requests_Exception object
-	 */
-	public static function parse_multiple(&$response, $request) {
-		try {
-			$url      = $request['url'];
-			$headers  = $request['headers'];
-			$data     = $request['data'];
-			$options  = $request['options'];
-			$response = self::parse_response($response, $url, $headers, $data, $options);
-		}
-		catch (Requests_Exception $e) {
-			$response = $e;
-		}
-	}
-
-	/**
-	 * Decoded a chunked body as per RFC 2616
-	 *
-	 * @see https://tools.ietf.org/html/rfc2616#section-3.6.1
-	 * @param string $data Chunked body
-	 * @return string Decoded body
-	 */
-	protected static function decode_chunked($data) {
-		if (!preg_match('/^([0-9a-f]+)(?:;(?:[\w-]*)(?:=(?:(?:[\w-]*)*|"(?:[^\r\n])*"))?)*\r\n/i', trim($data))) {
-			return $data;
-		}
-
-		$decoded = '';
-		$encoded = $data;
-
-		while (true) {
-			$is_chunked = (bool) preg_match('/^([0-9a-f]+)(?:;(?:[\w-]*)(?:=(?:(?:[\w-]*)*|"(?:[^\r\n])*"))?)*\r\n/i', $encoded, $matches);
-			if (!$is_chunked) {
-				// Looks like it's not chunked after all
-				return $data;
-			}
-
-			$length = hexdec(trim($matches[1]));
-			if ($length === 0) {
-				// Ignore trailer headers
-				return $decoded;
-			}
-
-			$chunk_length = strlen($matches[0]);
-			$decoded     .= substr($encoded, $chunk_length, $length);
-			$encoded      = substr($encoded, $chunk_length + $length + 2);
-
-			if (trim($encoded) === '0' || empty($encoded)) {
-				return $decoded;
-			}
-		}
-
-		// We'll never actually get down here
-		// @codeCoverageIgnoreStart
-	}
-	// @codeCoverageIgnoreEnd
-
-	/**
-	 * Convert a key => value array to a 'key: value' array for headers
-	 *
-	 * @param array $array Dictionary of header values
-	 * @return array List of headers
-	 */
-	public static function flatten($array) {
-		$return = array();
-		foreach ($array as $key => $value) {
-			$return[] = sprintf('%s: %s', $key, $value);
-		}
-		return $return;
-	}
-
-	/**
-	 * Convert a key => value array to a 'key: value' array for headers
-	 *
-	 * @codeCoverageIgnore
-	 * @deprecated Misspelling of {@see Requests::flatten}
-	 * @param array $array Dictionary of header values
-	 * @return array List of headers
-	 */
-	public static function flattern($array) {
-		return self::flatten($array);
-	}
-
-	/**
-	 * Decompress an encoded body
-	 *
-	 * Implements gzip, compress and deflate. Guesses which it is by attempting
-	 * to decode.
-	 *
-	 * @param string $data Compressed data in one of the above formats
-	 * @return string Decompressed string
-	 */
-	public static function decompress($data) {
-		if (substr($data, 0, 2) !== "\x1f\x8b" && substr($data, 0, 2) !== "\x78\x9c") {
-			// Not actually compressed. Probably cURL ruining this for us.
-			return $data;
-		}
-
-		if (function_exists('gzdecode')) {
-			// phpcs:ignore PHPCompatibility.FunctionUse.NewFunctions.gzdecodeFound -- Wrapped in function_exists() for PHP 5.2.
-			$decoded = @gzdecode($data);
-			if ($decoded !== false) {
-				return $decoded;
-			}
-		}
-
-		if (function_exists('gzinflate')) {
-			$decoded = @gzinflate($data);
-			if ($decoded !== false) {
-				return $decoded;
-			}
-		}
-
-		$decoded = self::compatible_gzinflate($data);
-		if ($decoded !== false) {
-			return $decoded;
-		}
-
-		if (function_exists('gzuncompress')) {
-			$decoded = @gzuncompress($data);
-			if ($decoded !== false) {
-				return $decoded;
-			}
-		}
-
-		return $data;
-	}
-
-	/**
-	 * Decompression of deflated string while staying compatible with the majority of servers.
-	 *
-	 * Certain Servers will return deflated data with headers which PHP's gzinflate()
-	 * function cannot handle out of the box. The following function has been created from
-	 * various snippets on the gzinflate() PHP documentation.
-	 *
-	 * Warning: Magic numbers within. Due to the potential different formats that the compressed
-	 * data may be returned in, some "magic offsets" are needed to ensure proper decompression
-	 * takes place. For a simple progmatic way to determine the magic offset in use, see:
-	 * https://core.trac.wordpress.org/ticket/18273
-	 *
-	 * @since 2.8.1
-	 * @link https://core.trac.wordpress.org/ticket/18273
-	 * @link https://secure.php.net/manual/en/function.gzinflate.php#70875
-	 * @link https://secure.php.net/manual/en/function.gzinflate.php#77336
-	 *
-	 * @param string $gz_data String to decompress.
-	 * @return string|bool False on failure.
-	 */
-	public static function compatible_gzinflate($gz_data) {
-		// Compressed data might contain a full zlib header, if so strip it for
-		// gzinflate()
-		if (substr($gz_data, 0, 3) === "\x1f\x8b\x08") {
-			$i   = 10;
-			$flg = ord(substr($gz_data, 3, 1));
-			if ($flg > 0) {
-				if ($flg & 4) {
-					list($xlen) = unpack('v', substr($gz_data, $i, 2));
-					$i         += 2 + $xlen;
-				}
-				if ($flg & 8) {
-					$i = strpos($gz_data, "\0", $i) + 1;
-				}
-				if ($flg & 16) {
-					$i = strpos($gz_data, "\0", $i) + 1;
-				}
-				if ($flg & 2) {
-					$i += 2;
-				}
-			}
-			$decompressed = self::compatible_gzinflate(substr($gz_data, $i));
-			if ($decompressed !== false) {
-				return $decompressed;
-			}
-		}
-
-		// If the data is Huffman Encoded, we must first strip the leading 2
-		// byte Huffman marker for gzinflate()
-		// The response is Huffman coded by many compressors such as
-		// java.util.zip.Deflater, Ruby’s Zlib::Deflate, and .NET's
-		// System.IO.Compression.DeflateStream.
-		//
-		// See https://decompres.blogspot.com/ for a quick explanation of this
-		// data type
-		$huffman_encoded = false;
-
-		// low nibble of first byte should be 0x08
-		list(, $first_nibble) = unpack('h', $gz_data);
-
-		// First 2 bytes should be divisible by 0x1F
-		list(, $first_two_bytes) = unpack('n', $gz_data);
-
-		if ($first_nibble === 0x08 && ($first_two_bytes % 0x1F) === 0) {
-			$huffman_encoded = true;
-		}
-
-		if ($huffman_encoded) {
-			$decompressed = @gzinflate(substr($gz_data, 2));
-			if ($decompressed !== false) {
-				return $decompressed;
-			}
-		}
-
-		if (substr($gz_data, 0, 4) === "\x50\x4b\x03\x04") {
-			// ZIP file format header
-			// Offset 6: 2 bytes, General-purpose field
-			// Offset 26: 2 bytes, filename length
-			// Offset 28: 2 bytes, optional field length
-			// Offset 30: Filename field, followed by optional field, followed
-			// immediately by data
-			list(, $general_purpose_flag) = unpack('v', substr($gz_data, 6, 2));
-
-			// If the file has been compressed on the fly, 0x08 bit is set of
-			// the general purpose field. We can use this to differentiate
-			// between a compressed document, and a ZIP file
-			$zip_compressed_on_the_fly = ((0x08 & $general_purpose_flag) === 0x08);
-
-			if (!$zip_compressed_on_the_fly) {
-				// Don't attempt to decode a compressed zip file
-				return $gz_data;
-			}
-
-			// Determine the first byte of data, based on the above ZIP header
-			// offsets:
-			$first_file_start = array_sum(unpack('v2', substr($gz_data, 26, 4)));
-			$decompressed     = @gzinflate(substr($gz_data, 30 + $first_file_start));
-			if ($decompressed !== false) {
-				return $decompressed;
-			}
-			return false;
-		}
-
-		// Finally fall back to straight gzinflate
-		$decompressed = @gzinflate($gz_data);
-		if ($decompressed !== false) {
-			return $decompressed;
-		}
-
-		// Fallback for all above failing, not expected, but included for
-		// debugging and preventing regressions and to track stats
-		$decompressed = @gzinflate(substr($gz_data, 2));
-		if ($decompressed !== false) {
-			return $decompressed;
-		}
-
-		return false;
-	}
-
-	public static function match_domain($host, $reference) {
-		// Check for a direct match
-		if ($host === $reference) {
-			return true;
-		}
-
-		// Calculate the valid wildcard match if the host is not an IP address
-		// Also validates that the host has 3 parts or more, as per Firefox's
-		// ruleset.
-		$parts = explode('.', $host);
-		if (ip2long($host) === false && count($parts) >= 3) {
-			$parts[0] = '*';
-			$wildcard = implode('.', $parts);
-			if ($wildcard === $reference) {
-				return true;
-			}
-		}
-
-		return false;
+		require_once __DIR__ . '/Requests/src/Autoload.php';
+		WpOrg\Requests\Autoload::register();
 	}
 }
diff --git a/wp-includes/class-wp-http-requests-hooks.php b/wp-includes/class-wp-http-requests-hooks.php
index dac64dd6eb..80e4eb7ef4 100644
--- a/wp-includes/class-wp-http-requests-hooks.php
+++ b/wp-includes/class-wp-http-requests-hooks.php
@@ -12,10 +12,10 @@
  *
  * @since 4.7.0
  *
- * @see Requests_Hooks
+ * @see WpOrg\Requests\Hooks
  */
 #[AllowDynamicProperties]
-class WP_HTTP_Requests_Hooks extends Requests_Hooks {
+class WP_HTTP_Requests_Hooks extends WpOrg\Requests\Hooks {
 	/**
 	 * Requested URL.
 	 *
diff --git a/wp-includes/class-wp-http-requests-response.php b/wp-includes/class-wp-http-requests-response.php
index 45f83e2c7a..821077656c 100644
--- a/wp-includes/class-wp-http-requests-response.php
+++ b/wp-includes/class-wp-http-requests-response.php
@@ -8,7 +8,7 @@
  */
 
 /**
- * Core wrapper object for a Requests_Response for standardisation.
+ * Core wrapper object for a WpOrg\Requests\Response for standardisation.
  *
  * @since 4.6.0
  *
@@ -19,7 +19,7 @@ class WP_HTTP_Requests_Response extends WP_HTTP_Response {
 	 * Requests Response object.
 	 *
 	 * @since 4.6.0
-	 * @var Requests_Response
+	 * @var \WpOrg\Requests\Response
 	 */
 	protected $response;
 
@@ -36,10 +36,10 @@ class WP_HTTP_Requests_Response extends WP_HTTP_Response {
 	 *
 	 * @since 4.6.0
 	 *
-	 * @param Requests_Response $response HTTP response.
-	 * @param string            $filename Optional. File name. Default empty.
+	 * @param \WpOrg\Requests\Response $response HTTP response.
+	 * @param string                   $filename Optional. File name. Default empty.
 	 */
-	public function __construct( Requests_Response $response, $filename = '' ) {
+	public function __construct( WpOrg\Requests\Response $response, $filename = '' ) {
 		$this->response = $response;
 		$this->filename = $filename;
 	}
@@ -49,7 +49,7 @@ class WP_HTTP_Requests_Response extends WP_HTTP_Response {
 	 *
 	 * @since 4.6.0
 	 *
-	 * @return Requests_Response HTTP response.
+	 * @return WpOrg\Requests\Response HTTP response.
 	 */
 	public function get_response_object() {
 		return $this->response;
@@ -60,11 +60,11 @@ class WP_HTTP_Requests_Response extends WP_HTTP_Response {
 	 *
 	 * @since 4.6.0
 	 *
-	 * @return \Requests_Utility_CaseInsensitiveDictionary Map of header name to header value.
+	 * @return \WpOrg\Requests\Utility\CaseInsensitiveDictionary Map of header name to header value.
 	 */
 	public function get_headers() {
 		// Ensure headers remain case-insensitive.
-		$converted = new Requests_Utility_CaseInsensitiveDictionary();
+		$converted = new WpOrg\Requests\Utility\CaseInsensitiveDictionary();
 
 		foreach ( $this->response->headers->getAll() as $key => $value ) {
 			if ( count( $value ) === 1 ) {
@@ -85,7 +85,7 @@ class WP_HTTP_Requests_Response extends WP_HTTP_Response {
 	 * @param array $headers Map of header name to header value.
 	 */
 	public function set_headers( $headers ) {
-		$this->response->headers = new Requests_Response_Headers( $headers );
+		$this->response->headers = new WpOrg\Requests\Response\Headers( $headers );
 	}
 
 	/**
diff --git a/wp-includes/class-wp-http.php b/wp-includes/class-wp-http.php
index 3d90085e49..d364cf4cd5 100644
--- a/wp-includes/class-wp-http.php
+++ b/wp-includes/class-wp-http.php
@@ -7,11 +7,11 @@
  * @since 2.7.0
  */
 
-if ( ! class_exists( 'Requests' ) ) {
-	require ABSPATH . WPINC . '/class-requests.php';
+if ( ! class_exists( 'WpOrg\Requests\Autoload' ) ) {
+	require ABSPATH . WPINC . '/Requests/src/Autoload.php';
 
-	Requests::register_autoloader();
-	Requests::set_certificate_path( ABSPATH . WPINC . '/certificates/ca-bundle.crt' );
+	WpOrg\Requests\Autoload::register();
+	WpOrg\Requests\Requests::set_certificate_path( ABSPATH . WPINC . '/certificates/ca-bundle.crt' );
 }
 
 /**
@@ -275,14 +275,14 @@ class WP_Http {
 		if ( empty( $url ) || empty( $parsed_url['scheme'] ) ) {
 			$response = new WP_Error( 'http_request_failed', __( 'A valid URL was not provided.' ) );
 			/** This action is documented in wp-includes/class-wp-http.php */
-			do_action( 'http_api_debug', $response, 'response', 'Requests', $parsed_args, $url );
+			do_action( 'http_api_debug', $response, 'response', 'WpOrg\Requests\Requests', $parsed_args, $url );
 			return $response;
 		}
 
 		if ( $this->block_request( $url ) ) {
 			$response = new WP_Error( 'http_request_not_executed', __( 'User has blocked requests through HTTP.' ) );
 			/** This action is documented in wp-includes/class-wp-http.php */
-			do_action( 'http_api_debug', $response, 'response', 'Requests', $parsed_args, $url );
+			do_action( 'http_api_debug', $response, 'response', 'WpOrg\Requests\Requests', $parsed_args, $url );
 			return $response;
 		}
 
@@ -299,7 +299,7 @@ class WP_Http {
 			if ( ! wp_is_writable( dirname( $parsed_args['filename'] ) ) ) {
 				$response = new WP_Error( 'http_request_failed', __( 'Destination directory for file streaming does not exist or is not writable.' ) );
 				/** This action is documented in wp-includes/class-wp-http.php */
-				do_action( 'http_api_debug', $response, 'response', 'Requests', $parsed_args, $url );
+				do_action( 'http_api_debug', $response, 'response', 'WpOrg\Requests\Requests', $parsed_args, $url );
 				return $response;
 			}
 		}
@@ -347,7 +347,7 @@ class WP_Http {
 			$options['max_bytes'] = $parsed_args['limit_response_size'];
 		}
 
-		// If we've got cookies, use and convert them to Requests_Cookie.
+		// If we've got cookies, use and convert them to WpOrg\Requests\Cookie.
 		if ( ! empty( $parsed_args['cookies'] ) ) {
 			$options['cookies'] = WP_Http::normalize_cookies( $parsed_args['cookies'] );
 		}
@@ -379,7 +379,7 @@ class WP_Http {
 		// Check for proxies.
 		$proxy = new WP_HTTP_Proxy();
 		if ( $proxy->is_enabled() && $proxy->send_through_proxy( $url ) ) {
-			$options['proxy'] = new Requests_Proxy_HTTP( $proxy->host() . ':' . $proxy->port() );
+			$options['proxy'] = new WpOrg\Requests\Proxy\HTTP( $proxy->host() . ':' . $proxy->port() );
 
 			if ( $proxy->use_authentication() ) {
 				$options['proxy']->use_authentication = true;
@@ -392,7 +392,7 @@ class WP_Http {
 		mbstring_binary_safe_encoding();
 
 		try {
-			$requests_response = Requests::request( $url, $headers, $data, $type, $options );
+			$requests_response = WpOrg\Requests\Requests::request( $url, $headers, $data, $type, $options );
 
 			// Convert the response into an array.
 			$http_response = new WP_HTTP_Requests_Response( $requests_response, $parsed_args['filename'] );
@@ -400,7 +400,7 @@ class WP_Http {
 
 			// Add the original object to the array.
 			$response['http_response'] = $http_response;
-		} catch ( Requests_Exception $e ) {
+		} catch ( WpOrg\Requests\Exception $e ) {
 			$response = new WP_Error( 'http_request_failed', $e->getMessage() );
 		}
 
@@ -417,7 +417,7 @@ class WP_Http {
 		 * @param array          $parsed_args HTTP request arguments.
 		 * @param string         $url         The request URL.
 		 */
-		do_action( 'http_api_debug', $response, 'response', 'Requests', $parsed_args, $url );
+		do_action( 'http_api_debug', $response, 'response', 'WpOrg\Requests\Requests', $parsed_args, $url );
 		if ( is_wp_error( $response ) ) {
 			return $response;
 		}
@@ -453,10 +453,10 @@ class WP_Http {
 	 * @since 4.6.0
 	 *
 	 * @param array $cookies Array of cookies to send with the request.
-	 * @return Requests_Cookie_Jar Cookie holder object.
+	 * @return WpOrg\Requests\Cookie\Jar Cookie holder object.
 	 */
 	public static function normalize_cookies( $cookies ) {
-		$cookie_jar = new Requests_Cookie_Jar();
+		$cookie_jar = new WpOrg\Requests\Cookie\Jar();
 
 		foreach ( $cookies as $name => $value ) {
 			if ( $value instanceof WP_Http_Cookie ) {
@@ -466,9 +466,9 @@ class WP_Http {
 						return null !== $attr;
 					}
 				);
-				$cookie_jar[ $value->name ] = new Requests_Cookie( $value->name, $value->value, $attributes, array( 'host-only' => $value->host_only ) );
+				$cookie_jar[ $value->name ] = new WpOrg\Requests\Cookie( $value->name, $value->value, $attributes, array( 'host-only' => $value->host_only ) );
 			} elseif ( is_scalar( $value ) ) {
-				$cookie_jar[ $name ] = new Requests_Cookie( $name, $value );
+				$cookie_jar[ $name ] = new WpOrg\Requests\Cookie( $name, (string) $value );
 			}
 		}
 
@@ -484,16 +484,16 @@ class WP_Http {
 	 *
 	 * @since 4.6.0
 	 *
-	 * @param string            $location URL to redirect to.
-	 * @param array             $headers  Headers for the redirect.
-	 * @param string|array      $data     Body to send with the request.
-	 * @param array             $options  Redirect request options.
-	 * @param Requests_Response $original Response object.
+	 * @param string                  $location URL to redirect to.
+	 * @param array                   $headers  Headers for the redirect.
+	 * @param string|array            $data     Body to send with the request.
+	 * @param array                   $options  Redirect request options.
+	 * @param WpOrg\Requests\Response $original Response object.
 	 */
 	public static function browser_redirect_compatibility( $location, $headers, $data, &$options, $original ) {
 		// Browser compatibility.
 		if ( 302 === $original->status_code ) {
-			$options['type'] = Requests::GET;
+			$options['type'] = WpOrg\Requests\Requests::GET;
 		}
 	}
 
@@ -502,12 +502,12 @@ class WP_Http {
 	 *
 	 * @since 4.7.5
 	 *
-	 * @throws Requests_Exception On unsuccessful URL validation.
+	 * @throws WpOrg\Requests\Exception On unsuccessful URL validation.
 	 * @param string $location URL to redirect to.
 	 */
 	public static function validate_redirects( $location ) {
 		if ( ! wp_http_validate_url( $location ) ) {
-			throw new Requests_Exception( __( 'A valid URL was not provided.' ), 'wp_http.redirect_failed_validation' );
+			throw new WpOrg\Requests\Exception( __( 'A valid URL was not provided.' ), 'wp_http.redirect_failed_validation' );
 		}
 	}
 
diff --git a/wp-includes/deprecated.php b/wp-includes/deprecated.php
index 26be922a77..62ff08b534 100644
--- a/wp-includes/deprecated.php
+++ b/wp-includes/deprecated.php
@@ -3654,7 +3654,7 @@ function post_permalink( $post = 0 ) {
  * @param string|bool $file_path Optional. File path to write request to. Default false.
  * @param int         $red       Optional. The number of Redirects followed, Upon 5 being hit,
  *                               returns false. Default 1.
- * @return \Requests_Utility_CaseInsensitiveDictionary|false Headers on success, false on failure.
+ * @return \WpOrg\Requests\Utility\CaseInsensitiveDictionary|false Headers on success, false on failure.
  */
 function wp_get_http( $url, $file_path = false, $red = 1 ) {
 	_deprecated_function( __FUNCTION__, '4.4.0', 'WP_Http' );
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index b9ed7dc2ec..620ff23ed7 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -976,7 +976,7 @@ function do_enclose( $content, $post ) {
  *
  * @param string $url        URL to retrieve HTTP headers from.
  * @param bool   $deprecated Not Used.
- * @return \Requests_Utility_CaseInsensitiveDictionary|false Headers on success, false on failure.
+ * @return \WpOrg\Requests\Utility\CaseInsensitiveDictionary|false Headers on success, false on failure.
  */
 function wp_get_http_headers( $url, $deprecated = false ) {
 	if ( ! empty( $deprecated ) ) {
diff --git a/wp-includes/http.php b/wp-includes/http.php
index f77d9a69a7..a8468ca17c 100644
--- a/wp-includes/http.php
+++ b/wp-includes/http.php
@@ -200,13 +200,13 @@ function wp_remote_head( $url, $args = array() ) {
  * Retrieve only the headers from the raw response.
  *
  * @since 2.7.0
- * @since 4.6.0 Return value changed from an array to an Requests_Utility_CaseInsensitiveDictionary instance.
+ * @since 4.6.0 Return value changed from an array to an WpOrg\Requests\Utility\CaseInsensitiveDictionary instance.
  *
- * @see \Requests_Utility_CaseInsensitiveDictionary
+ * @see \WpOrg\Requests\Utility\CaseInsensitiveDictionary
  *
  * @param array|WP_Error $response HTTP response.
- * @return \Requests_Utility_CaseInsensitiveDictionary|array The headers of the response, or empty array
- *                                                           if incorrect parameter given.
+ * @return \WpOrg\Requests\Utility\CaseInsensitiveDictionary|array The headers of the response, or empty array
+ *                                                                 if incorrect parameter given.
  */
 function wp_remote_retrieve_headers( $response ) {
 	if ( is_wp_error( $response ) || ! isset( $response['headers'] ) ) {
diff --git a/wp-includes/rest-api.php b/wp-includes/rest-api.php
index 64ceac73df..9898501cba 100644
--- a/wp-includes/rest-api.php
+++ b/wp-includes/rest-api.php
@@ -1414,7 +1414,7 @@ function rest_parse_request_arg( $value, $request, $param ) {
 function rest_is_ip_address( $ip ) {
 	$ipv4_pattern = '/^(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)$/';
 
-	if ( ! preg_match( $ipv4_pattern, $ip ) && ! Requests_IPv6::check_ipv6( $ip ) ) {
+	if ( ! preg_match( $ipv4_pattern, $ip ) && ! WpOrg\Requests\Ipv6::check_ipv6( $ip ) ) {
 		return false;
 	}
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 0aaad16cd1..5dc3a81274 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.2-alpha-54996';
+$wp_version = '6.2-alpha-54997';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.