==============
How to upgrade
==============

There are three ways to upgrade your Nextcloud server:

* With the :doc:`Updater <update>`.
* :doc:`Manually upgrading <manual_upgrade>` with the Nextcloud ``.tar`` archive
  from our `Download page <https://nextcloud.com/install/>`_.
* :doc:`Upgrading <package_upgrade>` via the snap packages.
* Manually upgrading is also an option for users on shared hosting; download
  and unpack the Nextcloud tarball to your PC. Delete your existing Nextcloud
  files, except ``data/`` and ``config/`` files, on your hosting account. Then
  transfer the new Nextcloud files to your hosting account, again
  preserving your existing ``data/`` and ``config/`` files.

When an update is available for your Nextcloud server, you will see a
notification at the top of your Nextcloud Web interface. When you click the
notification it brings you here, to this page.

**It is best to keep your Nextcloud server upgraded regularly**, and to install 
all point releases and major releases. 
Major releases are 18, 19 or 20. Point releases are intermediate releases for each major release. For example 18.0.4 and 19.0.2 are point releases. 

Nextcloud must be upgraded step by step: 
  * Before you can upgrade to the next major release, Nextcloud upgrades to the latest point release.
  * Then run the upgrade again to upgrade to the next major release's latest point release.
  * **You cannot skip major releases.** Please re-run the upgrade until you have reached the highest available (or applicable) release.
  * Example: 18.0.5 -> 18.0.11 -> 19.0.5 -> 20.0.2

**Wait for background migrations to finish after major upgrades**. After upgrading to a new major version, some migrations are scheduled to run 
as a background job. If you plan to upgrade directly to another major version (e.g. 24 -> 25 -> 26) you need to make sure these
migrations were executed before starting the next upgrade. To do so you should run the ``cron.php`` file 2-3 times, for example::

 $ sudo -u www-data php -f /var/www/nextcloud/cron.php

For more information about background jobs see :doc:`../configuration_server/background_jobs_configuration`.

**Upgrading is disruptive**. Your Nextcloud server will be put into maintenance
mode, so your users will be locked out until the upgrade is completed. Large
installations may take several hours to complete the upgrade. Nevertheless usual
upgrade times even for bigger installations are in the range of a few minutes.

.. warning:: **Downgrading is not supported** and risks corrupting your data! If
   you want to revert to an older Nextcloud version, make a new, fresh
   installation and then restore your data from backup. Before doing this,
   file a support ticket (if you have paid support) or ask for help in the
   Nextcloud forums to see if your issue can be resolved without downgrading.

Update notifications
--------------------

Nextcloud has an update notification app, that informs the administrator about
the availability of an update. Then you decide which update method to use.

.. figure:: images/2-updates.png
   :alt: Both update notifications displayed on Admin page.

   *Figure 1: The top banner is the update notification that is shown on every
   page, and the Updates section can be found in the admin page*

From there the web based updater can be used to fetch this new code. There is
also an CLI based updater available, that does exactly the same as the web
based updater but on the command line.

Prerequisites
-------------

You should always maintain :doc:`regular backups <backup>` and make a fresh
backup before every upgrade.

Then review third-party apps, if you have any, for compatibility with the new
Nextcloud release. Any apps that are not developed by Nextcloud show a 3rd party
designation. **Install unsupported apps at your own risk**. Then, before the
upgrade, all 3rd party apps must be disabled. After the upgrade is complete you
may re-enable them.

Maintenance mode
----------------

You can put your Nextcloud server into maintenance mode before performing
upgrades, or for performing troubleshooting or maintenance. Please see
:doc:`../configuration_server/occ_command` to learn how to put your server into
the maintenance mode (``maintenance:mode``) or execute repair commands
(``maintenance:repair``) with the ``occ`` command.

The :doc:`build-in Updater <update>` does this for you before replacing the
existing Nextcloud code with the code of the new Nextcloud version.

``maintenance:mode`` locks the sessions of logged-in users and prevents new
logins. This is the mode to use for upgrades. You must run ``occ`` as the HTTP
user, like this example on Ubuntu Linux::

 $ sudo -u www-data php occ maintenance:mode --on

You may also put your server into this mode by editing :file:`config/config.php`.
Change ``"maintenance" => false`` to ``"maintenance" => true``:

::

   <?php

    "maintenance" => true,

Then change it back to ``false`` when you are finished.

Manual steps during upgrade
---------------------------

Some operation can be quite time consuming. Therefore we decided not to add them
to the normal upgrade process. We recommend to run them manually after the upgrade
was completed. Below you find a list of this commands.

Long running migration steps
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

From time to time we do some changes to the database layout that take a lot of time,
but can be executed while Nextcloud stays online. Thus we moved them into a separate
command that an administrator can execute on the CLI without the need to lock the
instance into maintenance mode (at least for some of them). The instance will also
work without those changes applied, but performance is improved significantly by them.
There is also always an hint in the setup checks of the admin settings web interface.

Those include for example::

 $ sudo -u www-data php occ db:add-missing-columns
 $ sudo -u www-data php occ db:add-missing-indices
 $ sudo -u www-data php occ db:add-missing-primary-keys

You can use the ``--dry-run`` option to output the SQL queries instead of executing them.