#ajax callback is empty or not callable

Problem/Motivation from @yannickoo

Have you ever encountered that ui patterns is messing up things with the ajax callbacks? that screenshot is from "manage display" where i use a field group to map the fields.

In the logs:

Symfony\Component\HttpKernel\Exception\HttpException: The specified #ajax callback is empty or not callable. in Drupal\Core\Form\FormAjaxResponseBuilder->buildResponse() (line 67 of /var/www/html/docroot/core/lib/Drupal/Core/Form/FormAjaxResponseBuilder.php).

I can also try to store the configuration somehow and it looks good in frontend, just the form is weird.

That's my prop:

   url:
      title: URL
      $ref: "ui-patterns://url"

In the UI is something buggy, especially when using Component field group plugin and then trying to use:

• Data from a field
• Link
• Field prop: URI >> when selecting that i get the error message after the ajax callback

Then the form looks like that but when clicking Update i get this:

A random field formatter settings form appears from somewhere else

Proposed resolution

This issue may belong to https://www.drupal.org/project/ui_patterns_field_group because Yannick told us he "use a field group to map fields"

However the #AJAX error is a recurrent subject, happening from time to time (sometimes in https://www.drupal.org/project/display_builder ) , but never clearly identified and fixed, so this is the opportunity to investigate it at UI Patterns 2 main module level.