Saving A Model With Inlines In Django

This seems like a very easy problem, but I really can't figure out what's going on. I have some problems understanding the saving process on the Django admin site. This is the situ

Solution 1:

Apparently, the whole problem is located in the editable=settings.IS_DEV setting for the ID of every model. I don't know exactly why, but setting editable=False solves the problem.

I noticed I never had this problem on the production server, only on the ones flagged as development. Fortunately being able to set a specific ID was only useful in a very limited set of cases, so I won't miss it, but I feel like I just traded a problem with a less annoying one. If someone has a better solution, I'll be happy to change my mind and recognize that as the answer to this question.