Undefined array key "description_field_required" in \Drupal\file\Plugin\Field\FieldWidget\FileWidget::formElement

The warning can be prevented with the change in https://git.drupalcode.org/project/drupal/-/merge_requests/4574, but I don't know if there are any other effects of this field not being set.

I suspect that the proper fix may be in update hooks somewhere.

Thank you for reporting

So typically with these kind of issues we need to determine why this key isn't set. Could be masking a large problem.

Hi all,

Attaching a patch for D10 as well, in case anyone also needs it. Should apply cleanly using composer.

oily → changed the visibility of the branch 3380377-undefined-array-key to hidden.

Created new 11.x branch, hid old branch.

I grepped 'description_field_required' in core and it does not exist. However the code in the related issue #2320877 adds a key named 'description_field_required'.

@malcomio, Is it possible that whenever you encountered the warning message in the issue description that the site contained code that added that key. e.g. in a contributed module, composer patch or custom module?

Logically the only other way (I can think of) that that key could appear purely as a result of core code would be if it is dynamically generated eg by concatenating a string with a string from a variable. Then grepping 'description_field_required' would return nothing.

If the key is created outiside core eg in a contrib module then this is not a core issue and it can safely be closed.

I was trying to reproduce the issue and had no luck.

I tried following instances.
- In core check if there are any concatenated fields like "description_field_required"
Initially I did a quick search to see if we have dynamic variable. i.e. grep -r "_required'" core/
This didn't yielded any results.

Later I did same search with prefix i.e. "description_".
This didn't returned anything either.

My only guess is that if the patch from https://www.drupal.org/project/drupal/issues/2320877 ✨ Add a setting to make description a required field for file items Needs work issue is applied to core.
In-case it is not applied cleanly then $field_settings might not have key "description_field_required"
Reason is that, the error appears on line 249 which is close to the change in the above PR.

Another reason can be that above patch is used and update hook isn't called.
There is a "file_post_update_description_required()" which sets the values.
To confirm that there is a dedicated update test as well https://git.drupalcode.org/project/drupal/-/merge_requests/5876/diffs#di... which checks that "description_field_required" doesn't exist before update hook and it exists after update hook.

Apart from that I am in favour of postponing the issue unless we have clear steps to reproduce.

Please reopen again if you feel it is happening again with majority of users with the vanilla core.