[Django]-Multiple authentication backends configured and therefore must provide the `backend` argument or set the `backend` attribute on the user

I found the solution. call login() with backend argument like login(request, user, backend='django.contrib.auth.backends.ModelBackend')

here is full code:

def activate(request, uidb64, token, backend='django.contrib.auth.backends.ModelBackend'):
    try:
        uid = force_text(urlsafe_base64_decode(uidb64))
        user = User.objects.get(pk=uid)
    except (TypeError, ValueError, OverflowError, User.DoesNotExist):
        user = None

    if user is not None and account_activation_token.check_token(user, token):
        user.is_active = True
        user.profile.email_confirmed = True
        user.save()
        login(request, user, backend='django.contrib.auth.backends.ModelBackend')
        return redirect('home')
    else:
        return render(request, 'account_activation_invalid.html')

So in my case I simply hadn’t registered the user. Also did login(request, user, backend='django.contrib.auth.backends.ModelBackend')


To register user:

# register.py
from django.contrib.auth.models import User
cfg_user = 'user'
user = User.objects.create_user(username=cfg_user,
                                 email='email@domain.com',
                                 password='password')
print('registered user '+cfg_user)

# register.sh
python manage.py shell < register.py

If you are using the build in django class PasswordResetConfirmView, then you can fix it by adding:

post_reset_login_backend = "django.contrib.auth.backends.RemoteUserBackend"

Something like so:

from django.contrib.auth import views

class PasswordResetConfirmView(views.PasswordResetConfirmView):
    template_name = "reset_confirm.html"
    success_url = "/"
    post_reset_login = True
    post_reset_login_backend = "django.contrib.auth.backends.RemoteUserBackend"

If you set multiple authentication backends in settings.py as shown below:

# "core/settings.py"

AUTHENTICATION_BACKENDS = [
    "django.contrib.auth.backends.ModelBackend",
    "graphql_jwt.backends.JSONWebTokenBackend",
]

You need to set backend='django.contrib.auth.backends.ModelBackend' to login() in views.py as shown below then the error will be solved:

# "account/views.py"

from django.shortcuts import render, redirect
from .forms import NewUserForm
from django.contrib.auth import login
from django.contrib import messages

def register_request(request):
    if request.method == "POST":
        form = NewUserForm(request.POST)
        if form.is_valid():
            user = form.save()   # Here
            login(request, user, backend='django.contrib.auth.backends.ModelBackend')
            messages.success(request, "Registration successful.")
            return redirect("account:homepage")
        messages.error(request, "Unsuccessful registration. Invalid information.")
    form = NewUserForm()
    return render(request, "account/register.html", {"register_form":form})

In addition, when I set backend='graphql_jwt.backends.JSONWebTokenBackend' to login() in views.py as shown below then the error was solved as well in my case so if you set one of multiple authentication backends, the error may be solved as well:

# "account/views.py"

from django.shortcuts import render, redirect
from .forms import NewUserForm
from django.contrib.auth import login
from django.contrib import messages

def register_request(request):
    if request.method == "POST":
        form = NewUserForm(request.POST)
        if form.is_valid():
            user = form.save()   # Here
            login(request, user, backend='graphql_jwt.backends.JSONWebTokenBackend')
            messages.success(request, "Registration successful." )
            return redirect("account:homepage")
        messages.error(request, "Unsuccessful registration. Invalid information.")
    form = NewUserForm()
    return render(request, "account/register.html", {"register_form":form})

And, if you set only one "django.contrib.auth.backends.ModelBackend"
to AUTHENTICATION_BACKENDS as shown below:

# "core/settings.py"

AUTHENTICATION_BACKENDS = [
    "django.contrib.auth.backends.ModelBackend",
]

Or, if you don’t explicitly set AUTHENTICATION_BACKENDS itself in settings.py as shown below:

# "core/settings.py"

# AUTHENTICATION_BACKENDS = [
#     "django.contrib.auth.backends.ModelBackend",
# ]

You don’t need to set backend='django.contrib.auth.backends.ModelBackend' to login() in views.py because "django.contrib.auth.backends.ModelBackend" is set automatically.

In my case just simple assigning some of backend class from Django configuration to user work properly:

setattr(user, 'backend', 'django.contrib.auth.backends.RemoteUserBackend')

and then you can authenticate your user

As suggested here you need to set the backend of the user record. Before login(request, user) add the following line:

user.backend = 'django.contrib.auth.backends.ModelBackend'
...
login(request, user)