Fatal error: Uncaught Error: Class "PHPUnit\Framework\Constraint\Constraint" not found in /opt/lampp/htdocs/forum/flarum/vendor/symfony/mime/Test/Constraint/EmailAddressContains.php:19 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/forum/flarum/vendor/symfony/mime/Test/Constraint/EmailAddressContains.php on line 19