Fatal error: Uncaught Error: Class "ilAppointmentPresentationGUI" not found in /var/www/html/ilias/components/ILIAS/Calendar/classes/AppointmentPresentation/class.ilAppointmentPresentationUserGUI.php:10 Stack trace: #0 {main} thrown in /var/www/html/ilias/components/ILIAS/Calendar/classes/AppointmentPresentation/class.ilAppointmentPresentationUserGUI.php on line 10