Fatal error on accessing module uninstall page with Forum enabled

To reproduce, install the core forum module and then load admin/modules/uninstall.

Verified with 8.7, this looks working correctly. Issue not replicated.

Setting back to Needs Review & Triggering bots.

This probably needs tests?

The issue targets and old version (no longer supported) and I cannot reproduce on 8.7.5. If this issue still exists; please update with steps to reproduce for a supported version of Drupal.

I'm thinking Closed (outdated)?

I have tested this issue with 8.9x and I have not got the problem. When I visit the uninstall page.

Added steps to reproduce.

Hi,

There is no option to delete the forum vocabulary in admin UI. Since it's dependent on the forum module.

You can delete this vocabulary when you will directly enter the URL "admin/structure/taxonomy/manage/forums/delete" in the address bar.

Then you will get the above error after deleting vocabulary on the uninstall page.

There are no default options to delete that vocabulary due to dependency in the forum module.

The patch is working great. I didn't get the error on the uninstall page if forum vocabulary is deleted.

But I am not sure that we should delete the vocabulary in this way.

Thanks,
Ren

If user removes the vocabulary the forum functionality will be broken in many ways. I think a patch should prevent removal of forum vocabulary.
Note that vocabulary can also be removed through configuration system (drush cim, drush cdel, etc).

I think a patch should prevent removal of forum vocabulary.

So, in this case, we should change the title and description of this issue.

Hi all, I just had this problem in 8.8.4 and this seems like the proper place to recap what happened. If not, apologies! and please tell me where I should go :)

The website encountered an unexpected error. Please try again later.
TypeError: Argument 1 passed to Drupal\forum\ForumUninstallValidator::hasTermsForVocabulary() must implement interface Drupal\taxonomy\VocabularyInterface, null given, called in /home/ccaajj/public_html/conversate/web/core/modules/forum/src/ForumUninstallValidator.php on line 61 in Drupal\forum\ForumUninstallValidator->hasTermsForVocabulary() (line 103 of core/modules/forum/src/ForumUninstallValidator.php).

I went to uninstall the Forum module on the Uninstall module page.The checked checkbox in the left column was disabled. In the right column where the module description and other options can be seen by flipping the disclosure triangle, there were two bullet items saying essentially that all forum module content nodes had to be deleted and all forum vocabulary terms had to be deleted before the module could be disabled. So from the Manage Content and Manage Vocabs admin pages respectively, I deleted as asked.

Going back to the Uninstall page to finish the job, I got the error above. The Forum content type is still present and editable, and all the Forum permissions, links and fields all are still present, though /admin/forum gives a 404.

My experience aside, though I hope it will help in troubleshooting, any ideas on how this can be fixed? Drush pmu failed with the same error and composer remove didn't work because Forum is in core. Any advice appreciated!!

Thanks in advance,

-Chris

Hi again, I did find an answer for how to get the Uninstall page working again, which let me uninstall Forum after all

https://drupal.stackexchange.com/questions/259483/cant-uninstall-drupal-...

Basically, just create a replacement vocab named Forums and that lets the Uninstall page load as per usual.

-C

The workaround solution in #17 worked for me. It let me uninstall forums. Thanks

I tested this on Drupal 9.5.x and was able to reproduce the problem. Note that the delete option was not available when editing the forum vocabulary. One has to use the admin/structure/taxonomy/manage/forums/delete.

Perhaps this scenario can be added to \Drupal\Tests\forum\Functional\ForumUninstallTest?

I meant to update the IS.

Adding test cases.

In 9.5.x branch #26 patch applied successfully and clear the error after applying patch.

one tiny nitpick/question

+++ b/core/modules/forum/tests/src/Functional/ForumUninstallTest.php
@@ -159,4 +160,24 @@ public function testForumUninstallWithoutFieldStorage() {
+    \Drupal::service('module_installer')->install(['dblog']);

why are we installing dblog? I don't see where we use it further?

Yup, looks like I forgot to remove that. 👍
Updating the patch.

thanks, back to rtbc

I think it's a good idea to add a custom validator to prevent deletion of the forum vocabulary, but since there are sites already in this state, fixing this makes sense too.

Committed/pushed to 10.1.x and cherry-picked back to 9.5.x, thanks!

I've added the follow up, removing tag. #3315045: It is possible to delete the Forum vocabulary while Forum is installed .