[Answered ]-Url for 404 page in Django

That’s because you are in DEBUG mode. Set DEBUG to False in your settings and see if it works.

EDIT:
According to this link, you have to take a few more steps:

Step1: Create a 404.html file having your error message.

Step 2: Place 404.html in directory pointed by TEMPLATE_DIRS

Step 3: In urls.py set handler404 = 'app.views.custom_404'. This will be a you custom view which will return the 404.html page when Http 404 error occurs.

Step 4: Create you custom view in views.py:

def custom_404(request):
    return render_to_response('404.html')

Step 5: in settings.py , ALLOWED_HOSTS = ['hostname'], this will be a IP address from which you are running the django project (it can belocalhost).

Step 6: very important , in settings.py , make DEBUG=False, only then you will able to see the custom error page.

Its not necessary to specify the url for 404 in reg expression fashion as we always do, just follow what’s given below.
First of all you need to have a template for 404 message inside the templates folder(specified template directory in settings.py).
In the urls.py of project folder add this where the accounts (it can be any app) is an app of the same project:

project/urls.py

handler404 = 'accounts.views.page_not_found'

In accounts’ view add this:

accounts/views.py

def page_not_found(request):    
     """
       Page not found Error 404
     """
     response = render_to_response('404.html',context_instance=RequestContext(request))
     response.status_code = 404
     return response

Don’t forget to make necessary imports. Also don’t forget to change Debug=False in settings.py when testing in staging.