[FIXED] Cannot find default form templates after upgrading django from 3.x to 4.x

Issue

I just upgraded django from 3.x to 4.x. I am getting error for template not found:

TemplateDoesNotExist at /admin/login/
django/forms/errors/list/default.html

The template is in this location:

./lib/python3.8/site-packages/django/forms/templates/django/forms/errors/list/default.html

Django is trying to look in those locations:

django.template.loaders.filesystem.Loader: ./project/templates/django/forms/errors/list/default.html (Source does not exist)
django.template.loaders.app_directories.Loader: ./lib/python3.8/site-packages/django/contrib/admin/templates/django/forms/errors/list/default.html (Source does not exist)
django.template.loaders.app_directories.Loader: ./lib/python3.8/site-packages/django/contrib/auth/templates/django/forms/errors/list/default.html (Source does not exist)
django.template.loaders.app_directories.Loader: ./project/android/templates/django/forms/errors/list/default.html (Source does not exist)
django.template.loaders.app_directories.Loader: ./project/webapp/templates/django/forms/errors/list/default.html (Source does not exist)
django.template.loaders.app_directories.Loader: ./lib/python3.8/site-packages/oauth2_provider/templates/django/forms/errors/list/default.html (Source does not exist)
django.template.loaders.app_directories.Loader: ./lib/python3.8/site-packages/rest_framework/templates/django/forms/errors/list/default.html (Source does not exist)
django.template.loaders.app_directories.Loader: ./lib/python3.8/site-packages/debug_toolbar/templates/django/forms/errors/list/default.html (Source does not exist)
django.template.loaders.app_directories.Loader: ./lib/python3.8/site-packages/ajax_select/templates/django/forms/errors/list/default.html (Source does not exist)

So obviously, django is not even looking into it's own django.forms directory and I cannot figure out why. Is there some new settings on 4.x, that I am missing?

Edit: It is caused in all places, where there's a form and form.non_field_errors is called, because returned ErrorList class is using this template.

Solution

I worked out why these templates aren't found. If 'django.forms' isn't in the INSTALLED_APPS, the template directory isn't found. I've not checked the Django docs, but perhaps this is a side-effect of a tightening of the template search behaviour. The default setup has APP_DIRS: True, but i'm guessing you didn't have that in your TEMPLATES dict like me - as the default setup finds the template ok (ie if viewing the admin)

Here's what worked for me:

DJANGO_APPS = [
    "django.contrib.admin",
    "django.contrib.auth",
    "django.contrib.contenttypes",
    "django.contrib.sessions",
    "django.contrib.sites",
    "django.contrib.messages",
    "django.contrib.staticfiles",
    "django.contrib.humanize",
    "django.forms",
]

NB I use a cookie cutter based template which separates out Django apps from third party and project apps.

As pointed out by K.H. this is mentioned in the Django docs here, and is due to the new way Django renders forms through templates.

Answered By - stephendwolff