Translation source language is not set

I believe this is related to my issue: Follow-up to #2513226: Test for untranslatable entities before attempt to create a new translation

Yeah, but I have the same error as you "A fatal error occurred: Invalid translation language (und) specified" so I think it could have the same cause :)

Verified that this works. The code looks good as well. I'm not an expert enough to verify that this is the optimal solution to fix the problem but it certainly is a correct way to fix it. The problem - which you have probably figured out already, but noting here for reference - is that content_translation_entity_presave() asks $manager->getTranslationMetadata($entity)->getSource() for the source langcode and without this added code that ends up being und which then fails as described above.

I am still having similar fatal errors when switching the source language of an entity that has paragraphs attached, but I guess that's a separate issue.

Would be great to get this in.

Actually since this seems pretty related and touches the same lines of code uploading here, including an interdiff to #4.

I had already wondered about the isNew() check, not sure why that is needed to be honest. But the added code fixes my use-case of switching the source language. Again, if people think that this is a different problem I'm fine to open a new issue for that. But I thought it might be related. Again, I don't understand the hunk in #4.

On a separate note, we should probably fix the try-catch thing. It doesn't seem like it should be needed, very strange that that made the tests work.

I'll try this patch, we're having problems with translations.

So maybe to elaborate a bit more: After I had applied #4 I was no longer getting

A fatal error occurred: Invalid translation language (und) specified

as an error, but instead

A fatal error occurred: Invalid translation language (de) specified

Because now the source language (de) was being set correctly, but the paragraph entities had a different default language than the host entities.

This problem was mentioned yesterday on the user group meeting.

To make sure severe errors like this are cleanly handled in the long run, we need test coverage for this!

We also have this error occasionally.

On my experience this happens if you have paragraphs with images and you did not set everything about the image as translatable ( img, alt and title ).
You also have to do this directly on the field itself and not on the translation config page.

Had a problem applying this with #2631590: After previewing an entity with nested paragraphs, EntityChangedConstraintValidator sometimes leaves a node entity un-saveable already applied, so here's a patch for people already having that applied. (Or e.g. people using composer-patches that want to have both.)

I had the following situation:

paragraphs with #4 patch applied (https://www.drupal.org/files/issues/2597201-4.patch)

Multilingual site. Main language German, secondary language English.
A node in German with some paragraphs.
Add an English-language translation to this node (node/N/translations/add/de/en).
Click Save.

Get error:
The content has either been modified by another user, or you have already submitted modifications. As a result, your changes cannot be saved.

Your fix #19 helped, @tstoeckler.

Now I have these patches applied (in this order, using composer-patches):
#16 from https://www.drupal.org/node/2631590#comment-10806858 (https://www.drupal.org/files/issues/2597201-11--vs-2631590-16--do-not-te...)
#19 from @tstoeckler above (https://www.drupal.org/files/issues/2597201-11--vs-2631590-16--do-not-te...)

I am now able to save my DE->EN translations.

Even after #20 I'm still getting this error. The full error with trace is attached: 2597201-21.txt.

Confirming that the problem occurs when an image field needs to be translated. Only paragraphs with translatable image fields appear to be affected by this.

A workaround, if you don't need your image field to be translatable: you can go to Structure > Paragraph Types, edit your paragraph type, find the image field and de-select "Users may translate this field" See Screenshot: 2597201-21.png

Also.

RuntimeException: A config mapper can only contain configuration for a single language. in Drupal\config_translation\ConfigNamesMapper->getLangcode() (line 398 of core/modules/config_translation/src/ConfigNamesMapper.php).

Drupal\config_translation\Access\ConfigTranslationOverviewAccess->access(Object, Object)
call_user_func_array(Array, Array)
Drupal\Core\Access\AccessManager->performCheck('config_translation.access.overview', Object)
Drupal\Core\Access\AccessManager->check(Object, Object, NULL, 1)
Drupal\Core\Access\AccessManager->checkNamedRoute('entity.field_config.config_translation_overview.node', Array, Object, 1)
Drupal\Core\Menu\LocalTaskManager->getTasksBuild('entity.field_config.node_field_edit_form', Object)
Drupal\Core\Menu\LocalTaskManager->getLocalTasks('entity.field_config.node_field_edit_form', 0)
Drupal\Core\Menu\Plugin\Block\LocalTasksBlock->build()
Drupal\block\BlockViewBuilder::preRender(Array)
call_user_func('Drupal\block\BlockViewBuilder::preRender', Array)
Drupal\Core\Render\Renderer->doRender(Array)
Drupal\Core\Render\Renderer->doRender(Array, )
Drupal\Core\Render\Renderer->render(Array)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1)
__TwigTemplate_edc288ee8347d53b83394ea87e108c7f8bb91488104557c8f9cf0ff5ca68b892->doDisplay(Array, Array)
Twig_Template->displayWithErrorHandling(Array, Array)
Twig_Template->display(Array)
Twig_Template->render(Array)
twig_render_template('core/themes/seven/templates/page.html.twig', Array)
Drupal\Core\Theme\ThemeManager->render('page', Array)
Drupal\Core\Render\Renderer->doRender(Array, )
Drupal\Core\Render\Renderer->render(Array)
Drupal\Core\Template\TwigExtension->escapeFilter(Object, Array, 'html', NULL, 1)
__TwigTemplate_d036aeb834ab1c671967ea5be059fcb27a7f054364af6c3e210dbfce42492e38->doDisplay(Array, Array)
Twig_Template->displayWithErrorHandling(Array, Array)
Twig_Template->display(Array)
Twig_Template->render(Array)
twig_render_template('core/themes/classy/templates/layout/html.html.twig', Array)
Drupal\Core\Theme\ThemeManager->render('html', Array)
Drupal\Core\Render\Renderer->doRender(Array, )
Drupal\Core\Render\Renderer->render(Array)
Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}()
Drupal\Core\Render\Renderer->executeInRenderContext(Object, Object)
Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object, Object)
Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object, 'kernel.view', Object)
Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch('kernel.view', Object)
Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1)
Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1)
Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1)
Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1)
Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1)
Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1)
Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1)
Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1)
Stack\StackedHttpKernel->handle(Object, 1, 1)
Drupal\Core\DrupalKernel->handle(Object)

And thanks, The comment #21 mention to remove the option "users may translate it" and the paragraphs translation start working again.

From current investigation, it seems that there is a reliable way to detect if we need to update the source languages:
$form_state->getFormObject()->isDefaultFormLangcode($form_state)
Will return TRUE when editing the source. We will also use it to hide the controls intranslation.

Opened a "multilingual workflow bugs only meta issue" #2698239: Multilingual workflow bugs for a "general" discussion for these kind of bugs.

And investigations there turned out that isDefaultFormLangcode() is not reliable during a rebuild. We have found a better way to detect the translation controllers / forms, see the issue referenced by tduong.

Needs investigation after the referenced issue.

Could reproduce, discussed with @Berdir, this should fix the problem, still need to add tests for it.

#28 fixes my problem.

I have node containing a paragraphs field which contains a paragraph field that contains images and textareas. Before the patch, I would get a WSOD and the error, "Drupal\Core\Entity\EntityStorageException: Invalid translation language (und) specified. in Drupal\Core\Entity\Sql\SqlContentEntityStorage->save() (line 757 of /Applications/MAMP/htdocs/paragraphs/docroot/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php).

Added tests, let's see what test bot thinks about this.

Just tested manually against the latest dev and it seems to be working even without the patch, was this fixed somewhere else?

From discussion with Berdir:
We should have a core issue that fixes the uncaught exception. Core should not die().

Did you really reproduce with a proper translation_sync case?

yes, that's true, core should not die.
yes, tested with image field, some days ago I was able to reproduce the fail but not anymore.

Seems to be failling since the commit a9810ae. Added diff between that commit and main branch.

In the test the image field of the Images paragraph type has been not set as translatable. Added missing settings, some checks and comments.

Totally true! I knew there was something missing. Thank you @tduong!

Committed in attribution of everyone involved. Thx for getting this sorted out! :-)

I'm still having this issue when trying to generate content with devel.