Module development and code questions

I am using Drupal 9.4.5 and having the custom module code

class="placeholder">Symfony\Component\HttpKernel\Exception\HttpException</em>: The specified #ajax callback is empty or not callable. in <em class="placeholder">Drupal\Core\Form\FormAjaxResponseBuilder-&gt;buildResponse()</em> (line <em class="placeholder">67</em> of <em class="placeholder">core/lib/Drupal/Core/Form/FormAjaxResponseBuilder.php</em>).

Hi everyone,

I'm trying to perform some checks on an image before deleting it from "Medias".

I would like to verify that the image (media) is not in use before deleting it from the media.
For example, I have seen that if an image media is used in a custom field of a taxonomy, the row in the database table continues to exist after the corresponding media has been deleted, even after the Cron has been executed.

So I looked for the media delete form (media_delete_form) and tried a simple hook to add my own validation.

Hi, in form alter I programmatically assign the value to the entity in this way

$nodo->field_comune->entity ;

and It works, I return the title with the ID inside the brackets.
Now I am having difficulty in attributing the value within a callBack.
Using the same mechanism I tried this

I have this problem, I need migrate field stock from mi D7 website to D9, but in D7 use a Numeric field instead of 'Stock Level' field used for Commerce Stock. In the custom plugin i don,t have the correct parameters to modify, any help??

Hi everyone, How could I create a log where the records of the stock level in D9 are kept, just as I have done on my D7 page?

This is that I,ve got on D7

[![enter image description here][1]][1]

In D7 use a View like that[![enter image description here][2]][2]

But Use the module Rules with a custom PhP code that is:

Hello.
I'm trying to migrate a d6 drupal to 9, the problem is that migrate_drupal doesn't work with Drupal 6 so I'm using csv files to migrate the information.

I have check the d6_files.yml and d7_files.yml  files from drupal core modules, also I have read https://www.drupal.org/docs/drupal-apis/migrate-api/migrate-destination-...

This is my code: