Fatal error: Uncaught Error: Call to undefined function add_filter() in /users/laufgruppe-lvb/www/wordpress/wp-content/plugins/ubermenu/admin/custom.menu-item-types.php:4 Stack trace: #0 {main} thrown in /users/laufgruppe-lvb/www/wordpress/wp-content/plugins/ubermenu/admin/custom.menu-item-types.php on line 4