Fatal error: Uncaught Error: Class "ilContainerReferenceGUI" not found in /var/www/html/ilias/components/ILIAS/CategoryReference/classes/class.ilObjCategoryReferenceGUI.php:25 Stack trace: #0 {main} thrown in /var/www/html/ilias/components/ILIAS/CategoryReference/classes/class.ilObjCategoryReferenceGUI.php on line 25