Fatal error: Uncaught Error: Class 'PHPUnit\Framework\Constraint\Constraint' not found in C:\xampp\htdocs\admin\vendor\symfony\mime\Test\Constraint\EmailHasHeader.php:17 Stack trace: #0 {main} thrown in C:\xampp\htdocs\admin\vendor\symfony\mime\Test\Constraint\EmailHasHeader.php on line 17