django.conf.urls.url() was deprecated in Django 3.0, and is removed in Django 4.0+.
The easiest fix is to replace url() with re_path(). re_path uses regexes like url, so you only have to update the import and replace url with re_path.
from django.urls import include, re_path
from myapp.views import home
urlpatterns = [
re_path(r'^$', home, name="home"),
re_path(r'^myapp/', include('myapp.urls'),
]
Alternatively, you could switch to using path. path() does not use regexes, so you’ll have to update your URL patterns if you switch to path.
from django.urls import include, path
from myapp.views import home
urlpatterns = [
path('', home, name="home"),
path('myapp/', include('myapp.urls'),
]
If you have a large project with many URL patterns to update, you may find the django-upgrade library useful to update your urls.py files.