Fatal error: Uncaught Error: Interface "Sabre\DAV\ICollection" not found in /var/www/illumine/vendor/sabre/dav/lib/CalDAV/ICalendarObjectContainer.php:18 Stack trace: #0 {main} thrown in /var/www/illumine/vendor/sabre/dav/lib/CalDAV/ICalendarObjectContainer.php on line 18