Django - is not a registered namespace
You should just change you action url in your template:
<form action="{% url 'submit' %} "method='post'>
On the note of url namespaces...
In order to be able to call urls using home
namespace you should have in your main urls.py file line something like:
for django 1.x:
url(r'^', include('home.urls', namespace='home')),
for django 2.x and 3.x
path('', include(('home.urls', 'home'), namespace='home'))
In your main project, open url.py first. Then check, there should be app_name declared at first. If it is not, declare it.
For example, my app name is user info which is declared in url.py
app_name = "userinfo"
urlpatterns = [
url(r'home/', views.home, name='home'),
url(r'register/', views.registration, name='register')
]