404 Page not found and 500 Internal server errors generally occur on every website. When these errors occur, generally for Django application it will load a page showing the application settings. So to avoid settings open, we'll keep DEBUG=False in production mode. Nginx or apace by default serve 404 and 500 pages when DEBUG=False, which are not user-friendly. So in order to display better-looking UI to the end user, we'll customize the Django's built-in 404 and 500 pages.

By default, these error pages are handled by handlerxxx views. For example 404 errors will be served by handler404 view, similarly, 500 Internal server error will be handled by handler500. So in order to display our custom pages instead of web server's pages, we will override the Django's handlerxxx views.

def handler404(request):
    return render(request, '404.html', status=404)

def handler500(request):
    return render(request, '500.html', status=500)

Now just specify these in your urls.py as below.

handler404 = myapp.views.handler404
handler500 = myapp.views.handler500

In settings.py

You need to add your hostname in ALLOWED_HOSTS like:

ALLOWED_HOSTS = ['testsite.com', 'localhost']

With the above steps, we'll get to see your own custom error pages served by Django's views with better UI.