Fatal error: Uncaught Error: Interface "Sabre\DAV\ICollection" not found in /server/www/10.1.1.5/htdocs/vendor/sabre/dav/lib/CalDAV/ICalendarObjectContainer.php:20 Stack trace: #0 {main} thrown in /server/www/10.1.1.5/htdocs/vendor/sabre/dav/lib/CalDAV/ICalendarObjectContainer.php on line 20