🇩🇪Germany @avogler

I gave it a short try. Looks good for me.

Sadly I cannot reproduce it because this happened on an intermediate step while upgrading to Drupal 10. But the problem was degov_simplenews_form_alter() got invoked with an instance of SubscriptionsPageForm. This form had inherited getNewsletterIds() from SubscriptionsFormBase in the past but getNewsletterIds() got moved to SubscriptionsBlockForm some time ago (https://git.drupalcode.org/project/simplenews/-/commit/24d0fd954fe0d18f9...).

Added a patch/merge request.

avogler → created an issue.