Fixed #20667 - Removed discussion of DEBUG from tutorial.

    .. _Sentry: http://sentry.readthedocs.org/en/latest/

Customize the default error views

---------------------------------

Django includes default views and templates for several HTTP error codes. You

may want to override the default templates by creating the following templates

in your root template directory: ``404.html``, ``500.html``, ``403.html``, and

``400.html``. The default views should suffice for 99% of Web applications, but

if you desire to customize them, see these instructions which also contain

details about the default templates:

* :ref:`http_not_found_view`

* :ref:`http_internal_server_error_view`

* :ref:`http_forbidden_view`

* :ref:`http_bad_request_view`

Miscellaneous

=============

:meth:`~django.db.models.query.QuerySet.get`. It raises

:exc:`~django.http.Http404` if the list is empty.

Write a 404 (page not found) view

=================================

When you raise :exc:`~django.http.Http404` from within a view, Django

will load a special view devoted to handling 404 errors. It finds it

by looking for the variable ``handler404`` in your root URLconf (and

only in your root URLconf; setting ``handler404`` anywhere else will

have no effect), which is a string in Python dotted syntax -- the same

format the normal URLconf callbacks use. A 404 view itself has nothing

special: It's just a normal view.

You normally won't have to bother with writing 404 views. If you don't set

``handler404``, the built-in view :func:`django.views.defaults.page_not_found`

is used by default. Optionally, you can create a ``404.html`` template

in the root of your template directory. The default 404 view will then use that

template for all 404 errors when :setting:`DEBUG` is set to ``False`` (in your

settings module). If you do create the template, add at least some dummy

content like "Page not found".

.. warning::

    If :setting:`DEBUG` is set to ``False``, all responses will be

    "Bad Request (400)" unless you specify the proper :setting:`ALLOWED_HOSTS`

    as well (something like ``['localhost', '127.0.0.1']`` for

    local development).

A couple more things to note about 404 views:

* If :setting:`DEBUG` is set to ``True`` (in your settings module) then your

  404 view will never be used (and thus the ``404.html`` template will never

  be rendered) because the traceback will be displayed instead.

* The 404 view is also called if Django doesn't find a match after checking

  every regular expression in the URLconf.

Write a 500 (server error) view

===============================

Similarly, your root URLconf may define a ``handler500``, which points

to a view to call in case of server errors. Server errors happen when

you have runtime errors in view code.

Likewise, you should create a ``500.html`` template at the root of your

template directory and add some content like "Something went wrong".

Use the template system

=======================

  where you'll turn to find the details of a particular function or

  whathaveyou.

* If you are interested in deploying a project for public use, our docs have

  :doc:`several guides</howto/deployment/index>` for various deployment

  setups as well as a :doc:`deployment checklist</howto/deployment/checklist>`

  for some things you'll need to think about.

* Finally, there's some "specialized" documentation not usually relevant to

  most developers. This includes the :doc:`release notes </releases/index>` and

  :doc:`internals documentation </internals/index>` for those who want to add

.. function:: django.views.defaults.page_not_found(request, template_name='404.html')

When you raise an ``Http404`` exception, Django loads a special view devoted

to handling 404 errors. By default, it's the view

``django.views.defaults.page_not_found``, which either produces a very simple

"Not Found" message or loads and renders the template ``404.html`` if you

created it in your root template directory.

When you raise :exc:`~django.http.Http404` from within a view, Django loads a

special view devoted to handling 404 errors. By default, it's the view

:func:`django.views.defaults.page_not_found`, which either produces a very

simple "Not Found" message or loads and renders the template ``404.html`` if

you created it in your root template directory.

The default 404 view will pass one variable to the template: ``request_path``,

which is the URL that resulted in the error.

The ``page_not_found`` view should suffice for 99% of Web applications, but if

you want to override it, you can specify ``handler404`` in your URLconf, like

so::

you want to override it, you can specify ``handler404`` in your root URLconf

(setting ``handler404`` anywhere else will have no effect), like so::

    handler404 = 'mysite.views.my_custom_404_view'