diff --git a/wp-includes/blocks.php b/wp-includes/blocks.php
index 3bdcdcc452..41b8430f98 100644
--- a/wp-includes/blocks.php
+++ b/wp-includes/blocks.php
@@ -326,13 +326,15 @@ function register_block_type_from_metadata( $file_or_folder, $args = array() ) {
 		trailingslashit( $file_or_folder ) . 'block.json' :
 		$file_or_folder;
 
-	if ( ! file_exists( $metadata_file ) ) {
+	$is_core_block = str_starts_with( $file_or_folder, ABSPATH . WPINC );
+
+	if ( ! $is_core_block && ! file_exists( $metadata_file ) ) {
 		return false;
 	}
 
 	// Try to get metadata from the static cache for core blocks.
 	$metadata = false;
-	if ( str_starts_with( $file_or_folder, ABSPATH . WPINC ) ) {
+	if ( $is_core_block ) {
 		$core_block_name = str_replace( ABSPATH . WPINC . '/blocks/', '', $file_or_folder );
 		if ( ! empty( $core_blocks_meta[ $core_block_name ] ) ) {
 			$metadata = $core_blocks_meta[ $core_block_name ];
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 73014d8326..68ed4a2eea 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.3-alpha-55909';
+$wp_version = '6.3-alpha-55910';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.