Fatal error: Uncaught Error: Class 'Symfony\Component\Mime\Part\AbstractMultipartPart' not found in /home/edmedu/www/hana-edu.co.kr/sf4l/vendor/symfony/mime/Part/Multipart/AlternativePart.php:19 Stack trace: #0 {main} thrown in /home/edmedu/www/hana-edu.co.kr/sf4l/vendor/symfony/mime/Part/Multipart/AlternativePart.php on line 19