After adding django-debug to App, getting "'djdt' is not a registered namespace"

if this problem occurs when we set DEBUG to False then simply removing debugtoolbar middleware from the list fixed the problem.

• settings.py

MIDDLEWARE = [
    'debug_toolbar.middleware.DebugToolbarMiddleware',
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

if DEBUG is False:
    del MIDDLEWARE[0]

• urls.py

from django.conf import settings
from django.conf.urls import include

...

if settings.DEBUG:
    import debug_toolbar
    urlpatterns = [
        path('__debug__/', include(debug_toolbar.urls)),
    ] + urlpatterns

The error is due to we declare its middle but the module is not import in case DEBUG = FALSE. So, just check to add its middle in case DEDEUG is set TRUE

settings.py

MIDDLEWARE = [
    ...
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
....
]

if DEBUG:
    
    MIDDLEWARE = ['debug_toolbar.middleware.DebugToolbarMiddleware'] + MIDDLEWARE

urls.py

if settings.DEBUG:
    import debug_toolbar
    urlpatterns = [
        path('__debug__/', include(debug_toolbar.urls)),
    ] + urlpatterns

You need to manually add 'djdt' routes to the end of urls.py (if you use 'namespace' in your apps, add below codes to 'urls.py' in your project):

if settings.DEBUG:
    import debug_toolbar

    urlpatterns += [
        url(r'^__debug__/', include(debug_toolbar.urls)),
    ]