Fatal error: Uncaught Error: Class "Sabre\CardDAV\Backend\AbstractBackend" not found in C:\Apache24\htdocs\dle\engine\classes\composer\vendor\sabre\dav\lib\CardDAV\Backend\PDO.php:20 Stack trace: #0 {main} thrown in C:\Apache24\htdocs\dle\engine\classes\composer\vendor\sabre\dav\lib\CardDAV\Backend\PDO.php on line 20