Fatal error: Uncaught Error: Interface "Sabre\DAV\IFile" not found in /users/forscher/www/Baikal/vendor/sabre/dav/lib/CalDAV/ICalendarObject.php:21 Stack trace: #0 {main} thrown in /users/forscher/www/Baikal/vendor/sabre/dav/lib/CalDAV/ICalendarObject.php on line 21