Fatal error: Uncaught Error: Interface "ILIAS\BackgroundTasks\Observer" not found in /var/www/html/ilias/components/ILIAS/BackgroundTasks/src/Implementation/TaskManager/NonPersistingObserver.php:30 Stack trace: #0 {main} thrown in /var/www/html/ilias/components/ILIAS/BackgroundTasks/src/Implementation/TaskManager/NonPersistingObserver.php on line 30