Fatal error: Uncaught Error: Class 'WP_Customize_Panel' not found in C:\xampp\htdocs\aszhi\wp-includes\customize\class-wp-customize-themes-panel.php:17 Stack trace: #0 {main} thrown in C:\xampp\htdocs\aszhi\wp-includes\customize\class-wp-customize-themes-panel.php on line 17