django.core.exceptions.ImproperlyConfigured: Specifying a namespace in include() without providing an app_name is not supported.

django.core.exceptions.ImproperlyConfigured: Specifying a namespace in include() without providing an app_name is not supported. Set the app_name attribute in the included module, or pass a 2-tuple containing the list of patterns and app_name instead.

改成如下形式：

from django.contrib import admin
from django.urls import path
from django.conf.urls import url, include

urlpatterns = [
    path('admin/', admin.site.urls),
    url(r'^app/', include('App.urls')),
    url(r'^two/', include(('Two.urls', 'second'),namespace='second')),
]

参考链接：https://blog.csdn.net/jason_cdd/article/details/106953974