Error: [] operator not supported for strings in Drupal\menu_block\Plugin\Block\MenuBlock->getLinkTitleFromLink() (line 612 of modules/contrib/menu_block/src/Plugin/Block/MenuBlock.php).

I am attaching a patch that solves the problem in case anyone encounters the same problem.

Confirming that we also experienced this error:
- drupal 10.3.1
- php 8.2
- menu_block 8.x-1.11
Applying the patch resolved the php errors.

Marking this as RTBC

Can confirm experiencing the same error and that patch/MR work to resolve the problem.

Digging into the source of the problem on my site, I believe that the problem may be due to inconsistency in the Link Attributes Widget module data schema (perhaps a change that wasn't fully migrated?).

We use the Link Attributes Widget module → , which allows you to add attributes such as classes to menu links. For the page that was throwing this menu block error, re-saving the parent menu item resolved the error and allowed the page to show.

In the database, that parent page's 'link_options' field in the 'menu_link_content_data' table looked like this prior to re-saving:
a:1:{s:10:"attributes";a:1:{s:5:"class";s:0:"";}}

And like this after saving:
a:1:{s:10:"attributes";a:1:{s:5:"class";a:1:{i:0;s:0:"";}}}

The class is changed from a string to an array, allowing $attributes['class'][] = 'menu-item--active-trail'; to work without error.

The current patch/MR approach of setting $attributes['class'] to an empty array, regardless of what was there before seems to work for us, but I wonder if it's potentially removing classes that other users may want to keep?

I'm not 100% certain Link Attributes Widget is to blame for the ultimate problem here, but it seems likely given what is involved.

NW as of #8 the current implementation may override values. And it's unclear what's the root cause.

+1, also ran into this issue.

Same PHP & module combinations as mentioned previously.