Fatal error: Uncaught Error: Class "WP_REST_Controller" not found in C:\xampp\htdocs\wp-content\plugins\nextgen-gallery\src\REST\Admin\AttachToPost.php:11 Stack trace: #0 {main} thrown in C:\xampp\htdocs\wp-content\plugins\nextgen-gallery\src\REST\Admin\AttachToPost.php on line 11