diff --git a/wp-includes/rest-api/endpoints/class-wp-rest-widgets-controller.php b/wp-includes/rest-api/endpoints/class-wp-rest-widgets-controller.php
index 29daf4b1d9..b3bd5ae5ac 100644
--- a/wp-includes/rest-api/endpoints/class-wp-rest-widgets-controller.php
+++ b/wp-includes/rest-api/endpoints/class-wp-rest-widgets-controller.php
@@ -478,6 +478,7 @@ class WP_REST_Widgets_Controller extends WP_REST_Controller {
 				"widget-$id_base" => array(
 					$number => $instance,
 				),
+				'sidebar'         => $sidebar_id,
 			);
 		} elseif ( isset( $request['form_data'] ) ) {
 			$form_data = $request['form_data'];
diff --git a/wp-includes/version.php b/wp-includes/version.php
index e4f6180724..0992c6ed06 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.8-beta3-51238';
+$wp_version = '5.8-beta3-51239';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.