===================================
Upgrading Django to a newer version
===================================

While it can be a complex process at times, upgrading to the latest Django
version has several benefits:

* New features and improvements are added.
* Bugs are fixed.
* Older version of Django will eventually no longer receive security updates.
  (see :ref:`backwards-compatibility-policy`).
* Upgrading as each new Django release is available makes future upgrades less
  painful by keeping your code base up to date.

Here are some things to consider to help make your upgrade process as smooth as
possible.

Required Reading
================

If it's your first time doing an upgrade, it is useful to read the :doc:`guide
on the different release processes </internals/release-process>`.

Afterwards, you should familiarize yourself with the changes that were made in
the new Django version(s):

* Read the :doc:`release notes </releases/index>` for each 'final' release from
  the one after your current Django version, up to and including the version to
  which you plan to upgrade.
* Look at the :doc:`deprecation timeline</internals/deprecation>` for the
  relevant versions.

Pay particular attention to backwards incompatible changes to get a clear idea
of what will be needed for a successful upgrade.

Dependencies
============

In most cases it will be necessary to upgrade to the latest version of your
Django-related dependencies as well. If the Django version was recently
released or if some of your dependencies are not well-maintained, some of your
dependencies may not yet support the new Django version. In these cases you may
have to wait until new versions of your dependencies are released.

Installation
============

Once you're ready, it is time to :doc:`install the new Django version
</topics/install>`. If you are using virtualenv_ and it is a major upgrade, you
might want to set up a new environment with all the dependencies first.

Exactly which steps you will need to take depends on your installation process.
The most convenient way is to use pip_ with the ``--upgrade`` or ``-U`` flag:

.. code-block:: bash

   $ pip install -U Django

pip_ also automatically uninstalls the previous version of Django.

If you use some other installation process, you might have to manually
:ref:`uninstall the old Django version <removing-old-versions-of-django>` and
should look at the complete installation instructions.

.. _pip: http://www.pip-installer.org/
.. _virtualenv: http://www.virtualenv.org/

Testing
=======

When the new environment is set up, :doc:`run the full test suite
</topics/testing/overview>` for your application. In Python 2.7+, deprecation
warnings are silenced by default. It is useful to turn the warnings on so they
are shown in the test output (you can also use the flag if you test your app
manually using ``manage.py runserver``):

.. code-block:: bash

    $ python -Wall manage.py test

After you have run the tests, fix any failures. While you have the release
notes fresh in your mind, it may also be a good time to take advantage of new
features in Django by refactoring your code to eliminate any deprecation
warnings.

Deployment
==========

When you are sufficiently confident your app works with the new version of
Django, you're ready to go ahead and :doc:`deploy </howto/deployment/index>`
your upgraded Django project.

If you are using caching provided by Django, you should consider clearing your
cache after upgrading. Otherwise you may run into problems, for example, if you
are caching pickled objects as these objects are not guaranteed to be
pickle-compatible across Django versions. A past instance of incompatibility
was caching pickled :class:`~django.http.HttpResponse` objects, either
directly or indirectly via the :func:`~django.views.decorators.cache.cache_page`
decorator.
