Error: Call to a member function label() on null in Drupal\menu_link_content\Form\MenuLinkContentForm->form() (line 99 of /var/www/html/docroot/core/modules/menu_link_content/src/Form/MenuLinkContentForm.php).

@venkatadapa, Thank you, I have tested this on my project and found it is working as expected.

I am moving it for RTBC.

This patch has not been tested.

Is this something that should be fixed in the contributed module?

There must be missing tests of this is a core bug, and a regression.

I upgraded to Drupal 10.2.2 and I also can no longer add links to Group menus.

Patch #2 fixes the issue for me, but I have created this task in the Group Content Menu issue queue to get visibility with the maintainers of that module: https://www.drupal.org/project/group_content_menu/issues/3417879

In the meantime, I'm going to have to use the patch on this issue - so thanks!

Traced this back to #3110371: When adding a new menu link, restrict the available parents to the current menu. It isn't in 10.1 but is in 10.2. GCM does not have a full config backed menu. It never will. Additionally, the menu parent logic is overwritten by that module after this here. The patch in #2 seems like a decent solution. An entity load can fail to load (that's what we see here). We should check and handle appropriately.

Still needs tests, but this can be easily reproduced. In a test controller add something like:

  public function addLink(GroupContentMenuInterface $group_content_menu) {
    $menu_name = 'non-existent';
    $menu_link = $this->entityTypeManager()->getStorage('menu_link_content')->create([
      'menu_name' => $menu_name,
      'bundle' => 'menu_link_content',
    ]);
    return $this->entityFormBuilder()->getForm($menu_link);
  }

Just to mention that I applied the patch #2 and it works for me! Thanks.

Looks good and works well here, I pushed a small commit to address @graber's review.

I only changed a word in a comment, so I think it's fine for me to RTBC this :)

Made some comments on the MR with a suggested change.

Appears suggestions by @alexpott has been addressed.

Committed and pushed 84432de226 to 11.x and cf919c8960 to 10.3.x and 22add58ea6 to 10.2.x. Thanks!