Manual:Upgrading



Overview
First read the UPGRADE text file included in MediaWiki.


 * 1) Check the requirements
 * 2) Read the release notes
 * 3) Back up existing files and the database
 * 4) Unpack the new files
 * 5) Run the update script to check the database
 * 6) Upgrade extensions
 * 7) Test the update

Check requirements
MediaWiki requires:

PHP

 * PHP 5.0.x or later
 * We recommend using PHP 5.1.x or 5.2.x or 5.3.x, except 5.3.1,which has a bug.
 * Note that PHP 5.0.x under certain 64-bit platforms contains bugs which cause fundamental problems with MediaWiki. If running on an x86_64 (AMD64, EMT64) or other affected 64-bit platform, PHP 5.1.x or 5.2.x is required.

DBMS

 * MySQL 4.0.x or later
 * Version 3.x has not been supported since 1.6.0

or


 * PostgreSQL 8.1 or later
 * You will also require the tsearch2 and plpgsql modules, if running Postgres 8.1 or 8.2
 * see also Upgrading Postgres

Read the release notes
Within the distribution tarball, or within the files checked out/exported from SVN, there are a number of files with capitalised filenames, one of which contains the RELEASE-NOTES. Now's the time to open it up and find out what's been changed in this release.

Back up existing files and the database

 * Full instructions: Manual:Backing up a wiki

While the upgrade scripts are well-maintained and robust, things could still go pear-shaped. Before proceeding to update the database schema, make a full backup of the wiki, including both the database and the files:


 * the wiki's content, from the database. It may be a good idea to create an XML dump in addition to the SQL database dump.
 * MySQL:
 * text dump: mysqldump --all-databases > file.txt
 * xml dump: mysqldump --all-databases --xml > file.xml
 * PostgreSQL:
 * output for pg_restore: pg_dump --create -Fc -i yourwiki > yourwiki.db.dump
 * SQLite:
 * php maintenance/sqlite.php --backup-to filename
 * images and other media files (the contents of the images directory)
 * configuration files, i.e. LocalSettings.php</tt> and AdminSettings.php</tt> (if present)
 * MediaWiki's program files, including all skins and extensions, especially if you modified them.

Using a tarball package
If using a tarball package, decompress the file on the server where the old version of mediawiki is running. When untarring a tarball package normally a new directory for the new wiki version will be created and you will have to copy the new files and directories to your current wiki directory. Instead, to replace the existing files while decompressing and do this in one step, use this command:

$ tar xvzf mediawiki-.tar.gz -C /path/to/your/wiki/ --strip-components=1

On older Linux distributions (i.e. RHEL/CentOS 4.x) use:

$ tar xvzf mediawiki-.tar.gz -C /path/to/your/wiki/ --strip-path=1

For those people using an old version of tar (eg. GNU tar 1.13.x) which does not have --strip-components or --strip-path flags can uncompress the archive without the -C option and thereafter recursively copy the contents of the latest package into the previous wiki directory structure, as follows:

$ tar xvfz mediawiki-.tar.gz $ cp -r mediawiki-/* /path/to/your/wiki/

(Open)Solaris users should use gtar, or:

$ gzip -dc mediawiki-.tar.gz | tar xf -

Windows users can use 7zip to extract the tarball.

Using Subversion
If using Subversion, export the files into a clean location. Replace all existing files with the new versions, preserving the directory structure. The core code is now up to date.

Run the update script
Note: If you are upgrading to a pre-1.16 wiki, make sure there's an AdminSettings.php</tt> file in the wiki root, and it contains up to date information. The user needs full permissions (shell access) on the database.

The preferred method of performing the update is using the command-line maintenance script, although it is also possible to re-run the web-based installer.

Shell
From the command line, or an SSH shell or similar, change to the maintenance</tt> directory and execute the update script:

$ php update.php

(Note for simple installations on Windows (e. g. with XAMPP): You can run the update.php by executing it (doubleclick) when your .php-files are associated with the PHP.exe (if not, rightclick update.php, select Open With and browse to PHP.exe). Ensure that your server-application (e. g. Apache) and your database (e. g. MySQL) are running).

MediaWiki will inspect the existing schema and update it to work with the new code, adding tables and columns as needed.

What to do in case of "No superuser credentials" error
In case the scripts abort with a message:

"No superuser credentials could be found. Please provide the details of a user with appropriate permissions to update the database. See AdminSettings.sample for more details"

This means that you should check that you have defined $wgDBadminuser and $wgDBadminpassword in your LocalSettings.php file (in the main directory). These are the user and password needed by this script in order to access to the database.

Alternative 1: phpShell
If full permissions/shell access is not available, look at options such as phpShell, which emulates a command prompt using PHP functions. This might not work on some locked-down hosting setups.

When using such a solution, it is often desirable to skip the countdown period at the start of the script. Pass the --quick</tt> option to the update script to do so:

$ php update.php --quick

You may have to use "php5" instead of "php" if different versions are installed. For phpshell, the commandLine.inc and LocalSettings.php files may have to be edited so the script doesn't quit because phpshell is a run from the web server. It may instead be possible to sidestep this problem by running:

$ unset REQUEST_METHOD; php update.php --quick

This unsets the REQUEST_METHOD environment variable, the existence of which causes the script to quit, and then executes the script.

Alternative 2: Re-run the installer
An alternative to running the update script from the shell is to re-run the web installer. To do this, follow these steps:


 * 1) Rename LocalSettings.php</tt> to LocalSettings.old.php</tt>
 * 2) Make the config</tt> directory writable by the web server
 * 3) Make sure the database user has full rights to the database
 * 4) Browse to the wiki and start the installer
 * Fill in the form fields with the same values as was done during the previous version's installation.
 * When the installation process starts, the script will detect existing MediaWiki tables, and upgrade their schema.
 * When this is complete, a new LocalSettings.php</tt> will be generated.
 * 1) Delete the new configuration file (LocalSettings.php</tt>)
 * 2) Rename LocalSettings.old.php</tt> back to LocalSettings.php</tt>
 * 3) Restore permissions on the config</tt> directory

Upgrade extensions
Certain extensions have been updated in order to work with the new version of MediaWiki. Be sure to upgrade to the latest versions of such extensions. You might need to perform manual updates to custom extensions.

Test the update
Once the upgrade has been completed, browse to the wiki and check that the following operations work as expected:
 * Viewing pages
 * Editing pages
 * Uploading a file

Visit Special:Version and check that the version shown is correct and that the extensions are present.

How hard is it to upgrade?
If the only file you have modified is LocalSettings.php, and you are upgrading from 1.5 or later, the process is very simple. The amount of human work involved is only a few minutes. The database schema changes will take an amount of time proportional to the size of your database -- potentially hours for wikis with millions of pages, but for a more typical size of a few thousand pages, it is usually done in seconds.

Minor upgrades, within the same major version, say from 1.13.0 to 1.13.1, do not require any schema changes at all. You can just update the files.

Upgrading from 1.4 or earlier is potentially complicated because support for character sets other than UTF-8 was dropped, and the schema for storing bulk text changed. Please read the relevant section in the UPGRADE</tt> file.

Upgrading becomes difficult if you have modified our source code, and you don't want your changes to be overwritten. Tools such as diff and patch may be useful. There is also potential for trouble if you are using unmaintained extensions. Upgrade your extensions at the same time as you upgrade MediaWiki.

How do I upgrade from a really old version? In one step, or in several steps?
In one step, from your old version to the latest stable version. The vast majority of reports, as well as automated testing, indicate that doing it in one step works just fine.

If you have trouble believing this, read this mailing list post.

Should I back up first?
Short answer: yes.

Long answer: it depends on a) how much you value your data, b) how hard it is to create a backup and c) how confident you are with MySQL maintenance and administration.

An upgrade failure may leave your database in an inconsistent state, in between two versions. It may move an important table to a temporary name and then fail before it recreates the table correctly. It may change a field definition to an incorrect data type. It is very rare for an upgrade to cause irreversible data loss. More often, data corruption occurs which can be reversed by a skilled administrator.

Recovery is often complex. Volunteers on the support forums are unlikely to be impressed if you neglect to make a backup and then need help to recover from upgrade-related corruption. A better outcome is if you can revert to your backup, and then report the bug in the upgrade process which caused the corruption.

Can I keep my LocalSettings.php?
Yes, but you may have to make some minor changes. The format of LocalSettings.php is largely backwards compatible. Changes which break LocalSettings.php compatibility will be documented in the "configuration changes" section of the release notes.

Can my wiki stay online while it is upgrading?
Yes.

If you are upgrading between minor releases of MediaWiki, all you need to do is update the source files.

If you are upgrading between major releases of MediaWiki, the preferred procedure is as follows:


 * 1) Unpack the new version of MediaWiki into a new directory
 * 2) Prepare that new directory: copy your current LocalSettings.php from the old directory, copy any installed extensions and custom skins (if any).
 * 3) Enable read-only mode in LocalSettings.php of the old directory:


 * 1) Run the upgrade script in the new directory.
 * 2) Swap the old directory and the new directory.