Django 1.8: Problem with GenericRelation

[hemabe]

Hi,

I upgraded from Django 1.7 to 1.8 and now I get this error, if I try to access the content_object of a GenericRelation:

ERROR: 'NoneType' object has no attribute '_base_manager'

Context:

I overwrote the save-method in my app and try to get information about the object, which is being saved. I need

to know, of which type the generic relation is. So i try to get the content_object and this throws this error.

The code is as follows and works for Django 1.7:

    def save(self, update=False, *args, **kwargs):

        ...

        obj = self.content_object

        # throws an error 

Any idea are very welcome.

Thnka,

Hermi