Preview email broken in magento 2.4.8-p3: Call to undefined method Symfony\Component\Mime\Part\TextPart::getParts()

[rbrown]

Hi Jesse, I'm just making a note that previewing emails appears broken on 2.4.8-p3 with the following stack trace. I think magento have messed around with Email/Mime in recent releases, so I guess in previous versions there wasn't a Symfony\Component\Mime\Part\TextPart being returned from $message->getBody() before. Sending an email still works.

Stack trace:
#0 /magento2/vendor/yireo/magento2-emailtester2/Model/Mailer.php(190): Yireo\EmailTester2\Model\Mailer->getRawContentFromTransportBuilder()
#1 /magento2/vendor/yireo/magento2-emailtester2/Block/Adminhtml/Preview.php(68): Yireo\EmailTester2\Model\Mailer->getHtml()
#2 /magento2/vendor/yireo/magento2-emailtester2/Block/Adminhtml/Preview.php(57): Yireo\EmailTester2\Block\Adminhtml\Preview->setMailerOutput()
#3 /magento2/vendor/magento/framework/View/Element/AbstractBlock.php(223): Yireo\EmailTester2\Block\Adminhtml\Preview->_construct()
#4 /magento2/vendor/yireo/magento2-emailtester2/Block/Adminhtml/Preview.php(46): Magento\Framework\View\Element\AbstractBlock->__construct()
#5 /magento2/vendor/magento/framework/ObjectManager/Factory/AbstractFactory.php(121): Yireo\EmailTester2\Block\Adminhtml\Preview->__construct()
#6 /magento2/vendor/magento/framework/ObjectManager/Factory/Compiled.php(108): Magento\Framework\ObjectManager\Factory\AbstractFactory->createObject()
#7 /magento2/vendor/magento/framework/ObjectManager/ObjectManager.php(59): Magento\Framework\ObjectManager\Factory\Compiled->create()
#8 /magento2/vendor/magento/framework/View/Element/BlockFactory.php(44): Magento\Framework\ObjectManager\ObjectManager->create()
#9 /magento2/vendor/magento/framework/View/Layout/Generator/Block.php(272): Magento\Framework\View\Element\BlockFactory->createBlock()
#10 /magento2/vendor/magento/framework/View/Layout/Generator/Block.php(252): Magento\Framework\View\Layout\Generator\Block->getBlockInstance()
#11 /magento2/vendor/magento/framework/View/Layout.php(800): Magento\Framework\View\Layout\Generator\Block->createBlock()
#12 /magento2/vendor/magento/framework/View/Layout.php(783): Magento\Framework\View\Layout->_createBlock()
#13 /magento2/generated/code/Magento/Framework/View/Layout/Interceptor.php(248): Magento\Framework\View\Layout->createBlock()
#14 /magento2/vendor/yireo/magento2-emailtester2/Controller/Adminhtml/Index/Preview.php(96): Magento\Framework\View\Layout\Interceptor->createBlock()
#15 /magento2/vendor/magento/framework/Interception/Interceptor.php(58): Yireo\EmailTester2\Controller\Adminhtml\Index\Preview->execute()
#16 /magento2/vendor/magento/framework/Interception/Interceptor.php(138): Yireo\EmailTester2\Controller\Adminhtml\Index\Preview\Interceptor->___callParent()
#17 /magento2/vendor/magento/framework/Interception/Interceptor.php(153): Yireo\EmailTester2\Controller\Adminhtml\Index\Preview\Interceptor->{closure:Magento\Framework\Interception\Interceptor::___callPlugins():104}()
#18 /magento2/generated/code/Yireo/EmailTester2/Controller/Adminhtml/Index/Preview/Interceptor.php(23): Yireo\EmailTester2\Controller\Adminhtml\Index\Preview\Interceptor->___callPlugins()
#19 /magento2/vendor/magento/framework/App/Action/Action.php(111): Yireo\EmailTester2\Controller\Adminhtml\Index\Preview\Interceptor->execute()
#20 /magento2/vendor/magento/module-backend/App/AbstractAction.php(151): Magento\Framework\App\Action\Action->dispatch()
#21 /magento2/vendor/magento/framework/Interception/Interceptor.php(58): Magento\Backend\App\AbstractAction->dispatch()
#22 /magento2/vendor/magento/framework/Interception/Interceptor.php(138): Yireo\EmailTester2\Controller\Adminhtml\Index\Preview\Interceptor->___callParent()
#23 /magento2/vendor/magento/module-backend/App/Action/Plugin/Authentication.php(145): Yireo\EmailTester2\Controller\Adminhtml\Index\Preview\Interceptor->{closure:Magento\Framework\Interception\Interceptor::___callPlugins():104}()
#24 /magento2/vendor/magento/framework/Interception/Interceptor.php(135): Magento\Backend\App\Action\Plugin\Authentication->aroundDispatch()
#25 /magento2/vendor/magento/framework/Interception/Interceptor.php(153): Yireo\EmailTester2\Controller\Adminhtml\Index\Preview\Interceptor->{closure:Magento\Framework\Interception\Interceptor::___callPlugins():104}()
#26 /magento2/generated/code/Yireo/EmailTester2/Controller/Adminhtml/Index/Preview/Interceptor.php(32): Yireo\EmailTester2\Controller\Adminhtml\Index\Preview\Interceptor->___callPlugins()
#27 /magento2/vendor/magento/framework/App/FrontController.php(245): Yireo\EmailTester2\Controller\Adminhtml\Index\Preview\Interceptor->dispatch()
#28 /magento2/vendor/magento/framework/App/FrontController.php(212): Magento\Framework\App\FrontController->getActionResponse()
#29 /magento2/vendor/magento/framework/App/FrontController.php(146): Magento\Framework\App\FrontController->processRequest()
#30 /magento2/vendor/magento/framework/Interception/Interceptor.php(58): Magento\Framework\App\FrontController->dispatch()
#31 /magento2/vendor/magento/framework/Interception/Interceptor.php(138): Magento\Framework\App\FrontController\Interceptor->___callParent()
#32 /magento2/vendor/magento/framework/Interception/Interceptor.php(153): Magento\Framework\App\FrontController\Interceptor->{closure:Magento\Framework\Interception\Interceptor::___callPlugins():104}()
#33 /magento2/generated/code/Magento/Framework/App/FrontController/Interceptor.php(23): Magento\Framework\App\FrontController\Interceptor->___callPlugins()
#34 /magento2/vendor/magento/framework/App/Http.php(116): Magento\Framework\App\FrontController\Interceptor->dispatch()
#35 /magento2/vendor/magento/framework/Interception/Interceptor.php(58): Magento\Framework\App\Http->launch()
#36 /magento2/vendor/magento/framework/Interception/Interceptor.php(138): Magento\Framework\App\Http\Interceptor->___callParent()
#37 /magento2/vendor/magento/module-application-performance-monitor/Plugin/ApplicationPerformanceMonitor.php(38): Magento\Framework\App\Http\Interceptor->{closure:Magento\Framework\Interception\Interceptor::___callPlugins():104}()
#38 /magento2/vendor/magento/framework/Interception/Interceptor.php(135): Magento\ApplicationPerformanceMonitor\Plugin\ApplicationPerformanceMonitor->aroundLaunch()
#39 /magento2/vendor/magento/framework/Interception/Interceptor.php(153): Magento\Framework\App\Http\Interceptor->{closure:Magento\Framework\Interception\Interceptor::___callPlugins():104}()
#40 /magento2/generated/code/Magento/Framework/App/Http/Interceptor.php(23): Magento\Framework\App\Http\Interceptor->___callPlugins()
#41 /magento2/vendor/magento/framework/App/Bootstrap.php(264): Magento\Framework\App\Http\Interceptor->launch()
#42 /magento2/pub/index.php(30): Magento\Framework\App\Bootstrap->run()
#43 {main}```

[jissereitsma]

The fix for this might have been there already for some time, but I can see that the release never properly made it. Could you check if 1.7.9 fixes this for you?