Fatal error: Uncaught Error: Class "OCP\Collaboration\Reference\ADiscoverableReferenceProvider" not found in /home/tzuovhm/tzuovhm/apps_/calendar/lib/Reference/ReferenceProvider.php:20 Stack trace: #0 {main} thrown in /home/tzuovhm/tzuovhm/apps_/calendar/lib/Reference/ReferenceProvider.php on line 20