An incorrect behavior was reported on phpbb.de regarding the editor options for "Delete post" and the associated permissions. The error occurs when the user context has permanent delete permission enabled but soft delete permission is disabled. In this situation, however, the delete option (chechbox) for soft deletion is offered in the post editor and if you then try to delete the post with this option, phpBB will of course trigger an error message that deleting the post is not allowed.

I then first tracked the responsible permissions f_softdelete and f_delete in the source and added debug displays. In my further search I finally found the causal error in the prosilver style template of posting_editor.html. The code there causes the wrong checkbox to be displayed in the post editor if the combination f_delete:true and f_softdelete:false is active in the user context.

Reference:

https://www.phpbb.de/community/viewtopic.php?t=246192

PR follows...