Fatal error: Uncaught Error: Class "Symfony\Component\Mime\Part\AbstractMultipartPart" not found in /var/www/html/app/vendor/symfony/mime/Part/Multipart/RelatedPart.php:20 Stack trace: #0 {main} thrown in /var/www/html/app/vendor/symfony/mime/Part/Multipart/RelatedPart.php on line 20