Fatal error: Uncaught Error: Class 'WP_Customize_Panel' not found in /nfs/bronfs/uwfs/hw00/d67/cerse/wordpress/wp-includes/customize/class-wp-customize-themes-panel.php:17 Stack trace: #0 {main} thrown in /nfs/bronfs/uwfs/hw00/d67/cerse/wordpress/wp-includes/customize/class-wp-customize-themes-panel.php on line 17