Fatal error: Uncaught Error: Interface 'Sabre\CalDAV\ICalendarObjectContainer' not found in /home/malert/WebDAV/vendor/sabre/dav/lib/CalDAV/Schedule/IInbox.php:13 Stack trace: #0 {main} thrown in /home/malert/WebDAV/vendor/sabre/dav/lib/CalDAV/Schedule/IInbox.php on line 13