diff --git a/wp-admin/includes/update-core.php b/wp-admin/includes/update-core.php
index 329ec20152..77ede74c77 100644
--- a/wp-admin/includes/update-core.php
+++ b/wp-admin/includes/update-core.php
@@ -1656,6 +1656,13 @@ function _upgrade_422_find_genericons_files_in_folder( $directory ) {
 	}
 
 	$dirs = glob( $directory . '*', GLOB_ONLYDIR );
+	$dirs = array_filter(
+		$dirs,
+		function( $dir ) {
+			// Skip any node_modules directories.
+			return false === strpos( $dir, 'node_modules' );
+		}
+	);
 
 	if ( $dirs ) {
 		foreach ( $dirs as $dir ) {
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 78f3c0cdfb..20a041782c 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.9-alpha-51520';
+$wp_version = '5.9-alpha-51521';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.