Fatal error: Uncaught Error: Class "Symfony\Component\Mime\Part\AbstractMultipartPart" not found in /srv/www/sites/public/starter-cms/vendor/symfony/mime/Part/Multipart/AlternativePart.php:19 Stack trace: #0 {main} thrown in /srv/www/sites/public/starter-cms/vendor/symfony/mime/Part/Multipart/AlternativePart.php on line 19