Fatal error: Uncaught Error: Class 'Symfony\Component\Mime\Part\AbstractMultipartPart' not found in /var/www/typo3/vendor/symfony/mime/Part/Multipart/MixedPart.php:19 Stack trace: #0 {main} thrown in /var/www/typo3/vendor/symfony/mime/Part/Multipart/MixedPart.php on line 19