Fatal error: Uncaught Error: Class "Symfony\Component\Mime\Encoder\Base64Encoder" not found in /opt/lampp/htdocs/forum/flarum/vendor/symfony/mime/Encoder/Base64MimeHeaderEncoder.php:17 Stack trace: #0 {main} thrown in /opt/lampp/htdocs/forum/flarum/vendor/symfony/mime/Encoder/Base64MimeHeaderEncoder.php on line 17