Disabling async email sending using cli when pending emails in queue causes an error

[hostep]

Preconditions

1. Magento 2.2.5
2. PHP 7.0.31

Steps to reproduce

1. Make sure no cronjobs are active
2. Setup a clean Magento 2.2.5 installation (using composer)
3. Run bin/magento config:set sales_email/general/async_sending 1
4. In the backend, create a product
5. Flush caches
6. In the frontend, put the created product in your shopping cart, and go through the checkout so you have an order
7. Since async sales emails sending is enabled, there is now one email in the queue to be send
8. Now disable async sending, which will also trigger that the pending emails get send: bin/magento config:set sales_email/general/async_sending 0

Expected result

1. Pending emails get send
2. Async setting gets disabled
3. No errors

Actual result

1. No pending emails get send
2. Async setting doesn't get disabled
3. See error: Required parameter 'theme_dir' was not passed

Additional

1. I'm pretty convinced this used to work in an earlier version of Magento, but will have to do some more testing to see exactly where it worked and where it got broken.
2. Stack trace, should this be helpful:

#0  Magento\Framework\View\Design\Fallback\Rule\Simple->getPatternDirs() called at [vendor/magento/framework/View/Design/Fallback/Rule/Theme.php:78]
#1  Magento\Framework\View\Design\Fallback\Rule\Theme->getPatternDirs() called at [vendor/magento/framework/View/Design/Fallback/Rule/Composite.php:48]
#2  Magento\Framework\View\Design\Fallback\Rule\Composite->getPatternDirs() called at [vendor/magento/framework/View/Design/Fallback/Rule/ModularSwitch.php:50]
#3  Magento\Framework\View\Design\Fallback\Rule\ModularSwitch->getPatternDirs() called at [vendor/magento/framework/View/Design/FileResolution/Fallback/Resolver/Simple.php:124]
#4  Magento\Framework\View\Design\FileResolution\Fallback\Resolver\Simple->resolveFile() called at [vendor/magento/framework/View/Design/FileResolution/Fallback/Resolver/Simple.php:66]
#5  Magento\Framework\View\Design\FileResolution\Fallback\Resolver\Simple->resolve() called at [vendor/magento/framework/View/Design/FileResolution/Fallback/File.php:42]
#6  Magento\Framework\View\Design\FileResolution\Fallback\File->getFile() called at [vendor/magento/framework/View/Design/FileResolution/Fallback/TemplateFile.php:82]
#7  Magento\Framework\View\Design\FileResolution\Fallback\TemplateFile->getFile() called at [vendor/magento/framework/View/FileSystem.php:125]
#8  Magento\Framework\View\FileSystem->getTemplateFileName() called at [vendor/magento/framework/View/Element/Template/File/Resolver.php:61]
#9  Magento\Framework\View\Element\Template\File\Resolver->getTemplateFileName() called at [vendor/magento/framework/View/Element/Template.php:221]
#10 Magento\Framework\View\Element\Template->getTemplateFile() called at [vendor/magento/framework/View/Element/Template.php:300]
#11 Magento\Framework\View\Element\Template->_toHtml() called at [vendor/magento/framework/View/Element/AbstractBlock.php:667]
#12 Magento\Framework\View\Element\AbstractBlock->toHtml() called at [vendor/magento/module-payment/Helper/Data.php:218]
#13 Magento\Payment\Helper\Data->getInfoBlockHtml() called at [generated/code/Magento/Payment/Helper/Data/Interceptor.php:76]
#14 Magento\Payment\Helper\Data\Interceptor->getInfoBlockHtml() called at [vendor/magento/module-sales/Model/Order/Email/Sender/OrderSender.php:155]
#15 Magento\Sales\Model\Order\Email\Sender\OrderSender->getPaymentHtml() called at [vendor/magento/module-sales/Model/Order/Email/Sender/OrderSender.php:128]
#16 Magento\Sales\Model\Order\Email\Sender\OrderSender->prepareTemplate() called at [vendor/magento/module-sales/Model/Order/Email/Sender.php:77]
#17 Magento\Sales\Model\Order\Email\Sender->checkAndSend() called at [vendor/magento/module-sales/Model/Order/Email/Sender/OrderSender.php:102]
#18 Magento\Sales\Model\Order\Email\Sender\OrderSender->send() called at [vendor/magento/module-sales/Model/EmailSenderHandler.php:74]
#19 Magento\Sales\Model\EmailSenderHandler->sendEmails() called at [vendor/magento/module-sales/Observer/Virtual/SendEmails.php:50]
#20 Magento\Sales\Observer\Virtual\SendEmails->execute() called at [vendor/magento/framework/Event/Invoker/InvokerDefault.php:72]
#21 Magento\Framework\Event\Invoker\InvokerDefault->_callObserverMethod() called at [vendor/magento/framework/Event/Invoker/InvokerDefault.php:60]
#22 Magento\Framework\Event\Invoker\InvokerDefault->dispatch() called at [vendor/magento/framework/Event/Manager.php:66]
#23 Magento\Framework\Event\Manager->dispatch() called at [generated/code/Magento/Framework/Event/Manager/Proxy.php:95]
#24 Magento\Framework\Event\Manager\Proxy->dispatch() called at [vendor/magento/module-sales/Model/Config/Backend/Email/AsyncSending.php:32]
#25 Magento\Sales\Model\Config\Backend\Email\AsyncSending->afterSave() called at [vendor/magento/framework/Interception/Interceptor.php:58]
#26 Magento\Sales\Model\Config\Backend\Email\AsyncSending\Interceptor->___callParent() called at [vendor/magento/framework/Interception/Interceptor.php:138]
#27 Magento\Sales\Model\Config\Backend\Email\AsyncSending\Interceptor->Magento\Framework\Interception\{closure}() called at [vendor/magento/framework/Interception/Interceptor.php:153]
#28 Magento\Sales\Model\Config\Backend\Email\AsyncSending\Interceptor->___callPlugins() called at [generated/code/Magento/Sales/Model/Config/Backend/Email/AsyncSending/Interceptor.php:26]
#29 Magento\Sales\Model\Config\Backend\Email\AsyncSending\Interceptor->afterSave() called at [vendor/magento/framework/Model/ResourceModel/Db/AbstractDb.php:832]
#30 Magento\Framework\Model\ResourceModel\Db\AbstractDb->processAfterSaves() called at [vendor/magento/framework/Model/ResourceModel/Db/AbstractDb.php:418]
#31 Magento\Framework\Model\ResourceModel\Db\AbstractDb->save() called at [vendor/magento/module-config/Console/Command/ConfigSet/DefaultProcessor.php:85]
#32 Magento\Config\Console\Command\ConfigSet\DefaultProcessor->process() called at [vendor/magento/module-config/Console/Command/ConfigSet/ProcessorFacade.php:156]
#33 Magento\Config\Console\Command\ConfigSet\ProcessorFacade->processWithLockTarget() called at [vendor/magento/module-config/Console/Command/ConfigSetCommand.php:182]
#34 Magento\Config\Console\Command\ConfigSetCommand->Magento\Config\Console\Command\{closure}()
#35 call_user_func_array() called at [vendor/magento/module-config/Console/Command/EmulatedAdminhtmlAreaProcessor.php:59]
#36 Magento\Config\Console\Command\EmulatedAdminhtmlAreaProcessor->Magento\Config\Console\Command\{closure}()
#37 call_user_func_array() called at [vendor/magento/framework/App/State.php:186]
#38 Magento\Framework\App\State->emulateAreaCode() called at [vendor/magento/module-config/Console/Command/EmulatedAdminhtmlAreaProcessor.php:60]
#39 Magento\Config\Console\Command\EmulatedAdminhtmlAreaProcessor->process() called at [vendor/magento/module-config/Console/Command/ConfigSetCommand.php:184]
#40 Magento\Config\Console\Command\ConfigSetCommand->execute() called at [vendor/symfony/console/Command/Command.php:241]
#41 Symfony\Component\Console\Command\Command->run() called at [vendor/symfony/console/Application.php:843]
#42 Symfony\Component\Console\Application->doRunCommand() called at [vendor/symfony/console/Application.php:193]
#43 Symfony\Component\Console\Application->doRun() called at [vendor/magento/framework/Console/Cli.php:104]
#44 Magento\Framework\Console\Cli->doRun() called at [vendor/symfony/console/Application.php:117]
#45 Symfony\Component\Console\Application->run() called at [bin/magento:23]

[magento-engcom-team]

Hi @hostep. Thank you for your report.
To help us process this issue please make sure that you provided the following information:

• Summary of the issue
• Information on your environment
• Steps to reproduce
• Expected and actual results

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@hostep do you confirm that you was able to reproduce the issue on vanilla Magento instance following steps to reproduce?

• yes
• no

[hostep]

Small update here, this apparently never worked in any Magento version in contrast to what I thought earlier. Since the config:set command was only introduced in Magento 2.2.0, I tested that version, and the same problem occurs there.

I already tried applying the fix from #17344 (since that sounds very related), but that doesn't fix it unfortunately.

@hostep , thank you for your report.
We've acknowledged the issue and added to our backlog.

[dnsv]

Hi @hostep. I've reproduced the issue locally, then applied my changes from #17344 which fixed the issue for me. I've tested this using 2.2.5 and the latest 2.2-develop with magento's sample data.

[hostep]

Thanks very much for testing @dnsv!

I just re-tested and at first I couldn't see it being fixed with your PR.

But I noticed that under Content > Design > Configuration, there was no theme set yet, and that is apparently also needed for a fix, so I've configured 'Magento Luma' as the theme.

After doing that and re-running bin/magento config:set sales_email/general/async_sending 0, it now threw a different error: Missing required argument $debugHintsPath of Magento\Developer\Model\TemplateEngine\Plugin\DebugHints.

This error recently got fixed in #17984, so I've applied that patch as well, and now after your patch and this patch and running bin/magento config:set sales_email/general/async_sending 0, it finally works!
This was tested on Magento 2.2.6, so it might be slightly different then your test on Magento 2.2.5.

As an extra check, to make sure PR #17984 wasn't the only fix I needed, I re-did the test and only applied #17984 first.
After doing that, I was surprised to see that bin/magento config:set sales_email/general/async_sending 0 did actually work and didn't threw any errors, but when verifying if the email got send, it didn't. So I still needed the fix from PR #17344 to have the email getting send as well.

So summary, to be able to fix the bug reported in this issue on Magento 2.2.6:

• Make sure a theme is configured in Content > Design > Configuration for all scopes
• Apply fix from Fix "Required parameter 'theme_dir' was not passed" error when emulating an environment inside an emulated area #17344
• Apply fix from Implemeted MAGETWO-81170: Missing $debugHintsPath when sending email … #17984

I feel like it should also work when no theme is configured as it should fall back to the default one (Magento Luma), so that is probably some other small bug somewhere. But in theory, all production environments will most likely have a theme configured properly, so this is a less important bug.

I'll leave this issue open for now, since none of the two PR's mentioned above are merged yet.