Fatal error: Uncaught Error: Class 'PHPUnit\Framework\Constraint\Constraint' not found in C:\xampp\htdocs\plugins\Symfony\Component\Mailer\Test\Constraint\EmailIsQueued.php:17 Stack trace: #0 {main} thrown in C:\xampp\htdocs\plugins\Symfony\Component\Mailer\Test\Constraint\EmailIsQueued.php on line 17