diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index f7ee143c57..b1f74c68ac 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -4038,6 +4038,10 @@ function _wp_json_prepare_data( $data ) {
  * @param int   $status_code The HTTP status code to output.
  */
 function wp_send_json( $response, $status_code = null ) {
+	if ( defined( 'REST_REQUEST' ) && REST_REQUEST ) {
+		_doing_it_wrong( __FUNCTION__, __( 'Return a WP_REST_Response or WP_Error object from your callback when using the REST API.' ), '5.5.0' );
+	}
+
 	if ( ! headers_sent() ) {
 		header( 'Content-Type: application/json; charset=' . get_option( 'blog_charset' ) );
 		if ( null !== $status_code ) {
diff --git a/wp-includes/rest-api.php b/wp-includes/rest-api.php
index e0387500f0..6baef3df49 100644
--- a/wp-includes/rest-api.php
+++ b/wp-includes/rest-api.php
@@ -184,6 +184,8 @@ function rest_api_default_filters() {
 		add_filter( 'deprecated_function_trigger_error', '__return_false' );
 		add_action( 'deprecated_argument_run', 'rest_handle_deprecated_argument', 10, 3 );
 		add_filter( 'deprecated_argument_trigger_error', '__return_false' );
+		add_action( 'doing_it_wrong_run', 'rest_handle_doing_it_wrong', 10, 3 );
+		add_filter( 'doing_it_wrong_trigger_error', '__return_false' );
 	}
 
 	// Default serving.
@@ -597,6 +599,33 @@ function rest_handle_deprecated_argument( $function, $message, $version ) {
 	header( sprintf( 'X-WP-DeprecatedParam: %s', $string ) );
 }
 
+/**
+ * Handles _doing_it_wrong errors.
+ *
+ * @since 5.5.0
+ *
+ * @param string      $function The function that was called.
+ * @param string      $message  A message explaining what has been done incorrectly.
+ * @param string|null $version  The version of WordPress where the message was added.
+ */
+function rest_handle_doing_it_wrong( $function, $message, $version ) {
+	if ( ! WP_DEBUG || headers_sent() ) {
+		return;
+	}
+
+	if ( is_null( $version ) ) {
+		/* translators: Developer debugging message. 1: PHP function name, 2: Explanatory message */
+		$string = __( '%1$s (%2$s)' );
+		$string = sprintf( $string, $function, $message );
+	} else {
+		/* translators: Developer debugging message. 1: PHP function name, 2: Version information message, 3: Explanatory message. */
+		$string = __( '%1$s (since %2$s; %3$s)' );
+		$string = sprintf( $string, $function, $version, $message );
+	}
+
+	header( sprintf( 'X-WP-DoingItWrong: %s', $string ) );
+}
+
 /**
  * Sends Cross-Origin Resource Sharing headers with API requests.
  *
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 7a39279881..106206156f 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.5-alpha-48360';
+$wp_version = '5.5-alpha-48361';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.