django autoupdate user; save() got an unexpected keyword argument 'force_insert'

As a general rule, you should only override the save() method in the model itself, not in some model admin.

When overriding the save() method in a model, you should always use (*args, **kwargs) to be safe. You have no way of knowing which specific parameters are being used when a specific model is being saved.

Your Activity model should contain a method like this:

def save(self, *args, **kwargs):
    '''do your custom stuff here'''
    return super(Activity, self).save(*args, **kwargs)

update

If you have overridden save() method of Activity or some other Models that get saved in meanwhile, but forgotten to accept force_insert as keyword argument, this error could happen:

def save(self):
   ...
# should be
def save(self, force_insert=False, force_update=False, using=None):
    ...
# or at least
def save(self, **kwargs):
    ...

Check the trackback to locate the failed save

---

Your code does not fully follow the code from b-list.org, try:

def save_model(self, request, obj, form, change): 
    if not change:
        obj.cruser = request.user
    obj.save()