Fatal error: Uncaught Error: Interface "Symfony\Component\Mime\Header\HeaderInterface" not found in /home/matrixweb/public_html/whmcs2022/whmcs/vendor/symfony/mime/Header/AbstractHeader.php:21 Stack trace: #0 {main} thrown in /home/matrixweb/public_html/whmcs2022/whmcs/vendor/symfony/mime/Header/AbstractHeader.php on line 21