Fatal error: Uncaught Error: Call to undefined function add_action() in /users/laufgruppe-lvb/www/wordpress/wp-content/plugins/eventon-tickets/includes/admin/class-admin-ajax.php:19 Stack trace: #0 /users/laufgruppe-lvb/www/wordpress/wp-content/plugins/eventon-tickets/includes/admin/class-admin-ajax.php(458): evotx_admin_ajax->__construct() #1 {main} thrown in /users/laufgruppe-lvb/www/wordpress/wp-content/plugins/eventon-tickets/includes/admin/class-admin-ajax.php on line 19