Fatal error: Uncaught Error: Class "Sabre\DAVACL\PrincipalCollection" not found in D:\xampp\htdocs\pimcore\my-project\vendor\sabre\dav\lib\CalDAV\Principal\Collection.php:21 Stack trace: #0 {main} thrown in D:\xampp\htdocs\pimcore\my-project\vendor\sabre\dav\lib\CalDAV\Principal\Collection.php on line 21