Django. The current URL, , didn't match any of these - Python

from django.conf.urls import include, url
from django.contrib import admin
 
urlpatterns = [
    url(r'^admin/', admin.site.urls),
    url(r'^polls/', include('polls.urls')),
]

from django.http import HttpResponse
 
def index(request):
    return HttpResponse("Hello, world. You're at the polls index.")

from django.conf.urls import url
 
from . import views
 
urlpatterns = [
    url(r'^', views.index, name='index'),
]