Fatal error: Uncaught Error: Class "Symfony\Component\Mime\Header\AbstractHeader" not found in /home/matrixweb/public_html/whmcs2022/whmcs/vendor/symfony/mime/Header/DateHeader.php:19 Stack trace: #0 {main} thrown in /home/matrixweb/public_html/whmcs2022/whmcs/vendor/symfony/mime/Header/DateHeader.php on line 19