Fatal error: Uncaught Error: Class "Sabre\DAVACL\PrincipalCollection" not found in /var/www/illumine/vendor/sabre/dav/lib/CalDAV/Principal/Collection.php:19 Stack trace: #0 {main} thrown in /var/www/illumine/vendor/sabre/dav/lib/CalDAV/Principal/Collection.php on line 19