diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-sidebars-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-sidebars-controller.php
index 357e35814a..50c84f1dd9 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-sidebars-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-sidebars-controller.php
@@ -304,7 +304,7 @@ class WP_REST_Sidebars_Controller extends WP_REST_Controller {
 				}
 			);
 
-			$sidebar['widgets'] = $widgets;
+			$sidebar['widgets'] = array_values( $widgets );
 		}
 
 		$schema = $this->get_item_schema();
diff --git a/wp-includes/version.php b/wp-includes/version.php
index f4fba08b7f..59a2ac79a8 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.9-alpha-51375';
+$wp_version = '5.9-alpha-51377';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.