Fatal error: Uncaught Error: Class "Sabre\DAV\Collection" not found in D:\xampp\htdocs\pimcore\my-project\vendor\sabre\dav\lib\CalDAV\Schedule\Inbox.php:20 Stack trace: #0 {main} thrown in D:\xampp\htdocs\pimcore\my-project\vendor\sabre\dav\lib\CalDAV\Schedule\Inbox.php on line 20