I am using social login in my Django app. So, I have added additional backends in my settings.py file.
settings.py
AUTHENTICATION_BACKENDS = [ \'django.
You already have the user when you save the form, so you don't need to call authenticate since you already provide the backend when calling login():
authenticate
login()
user = form.save() login(request, user, backend='django.contrib.auth.backends.ModelBackend')