Manual:Upgrading



Basic 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 or later
 * Either MySQL or later, PostgreSQL 8.3 or later or  SQLite 3

If you are using PostgreSQL, please read also Upgrading Postgres.

For more information, please read the system requirements and compatibility.

Read the release notes
Within the distribution tarball, or within the files checked out/exported from Git, there are a number of files with capitalised filenames, one of which contains the RELEASE-NOTES (wiki). 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 awry. 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, (make sure you get the character set specified correctly, first check LocalSettings.php). It may be a good idea to create an XML dump in addition to the SQL database dump.
 * MySQL:
 * SQL dump: mysqldump --user=xxx --password=xxx  file in the MediaWiki root folder, you may receive errors referring to  .  Deleting, or renaming, the   file will resolve this error.  The   file, also in the MediaWiki root folder, can serve as a template should you enable profiling in the future.

Run the update script
You can upgrade MediaWiki either from the command line or from the web. If you have shell access to your server, upgrading from the command line is recommended, since this reduces the risk of the upgrade process being interrupted by a timeout or connection reset.

Command line
Access the command line of your server or an SSH shell or similar. You can access the command line by connecting to your server via SSH. If the local PC you are working on runs Microsoft Windows, you will need a tool like PuTTY to use SSH. From the command line or the Shell, change to the maintenance directory and execute the update script:

$ php update.php

Note for simple installations on Windows (e.g. with XAMPP): First make sure that your web server (such as Apache) and your database (such as MySQL) are running. Then run update.php: right-click it, select Open With, and browse to PHP.exe. The resulting command prompt window will likely autoclose when the schema upgrade completes.

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. (Note: Prior to MediaWiki 1.16, these variables were located in . This file was removed in 1.16 and the variables were moved to LocalSettings.php.)

What to do in case of "unexpected T_STRING" error
Individuals running update.php from the command line may encounter the following error: syntax error, unexpected T_STRING, expecting T_OLD_FUNCTION or T_FUNCTION or T_VAR or '}' \ in ~/maintenance/commandLine.inc on line 13

This error occurs when update.php is run from php4.

Individuals who have their site hosted by providers who provide both php4 and php5 should take the following steps:
 * 1) from the command line, enter the command 'whereis php5'
 * 2) once you have discerned the location of the php5 path, list the contents of php5/bin directory
 * 3) once you've determined the name of the php executable (either php or php5), type in the entire path to execute update.php

Below is an example: $ whereis php5 $ ls -la /usr/local/php5/bin $ /usr/local/php5/bin/php update.php

What to do in case of 'register_argc_argv is set to false' error
You may encounter the error: Cannot get command line arguments, register_argc_argv is set to false

register_argc_argv=true
 * 1) Go to ~/maintenance. Either edit an existing 'php.ini' file, or create one.
 * 2) Add a line as follows:
 * 1) Re-run php update.php

Web updater

 * See also update.php

If your database is already big and in high production usage, then you should not be using the Web updater. In that case you should use update.php from the command-line interface (not from the web). What exactly is "too big" depends on your server (e.g. on its performance, the load and on how long PHPs maximum execution time allows the script to run). If your wiki is too big for the web updater and your hosting provider does not allow command-line access, then you need to migrate your wiki to a hosting account that does have shell access.


 * 1) Always backup before performing database maintenance.
 * 2) Navigate to /mw-config/. For example, if your wiki is at  http://example.org/w/index.php , then navigate to  http://example.org/w/mw-config/ .
 * 3) Select your language and click continue.
 * 4) The existing installation should be detected. Follow the instructions on the screen to upgrade it. If asked for the "upgrade key", open your LocalSettings.php file and look for the key assigned to $wgUpgradeKey.

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. The database needs no update, hence it is not necessary to run the installer script.

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 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, patch, Meld or WinMerge 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.

If you have modified the skin or use a custom skin you very likely will have to adjust it to work again with the new version of MediaWiki.
 * Tip: instead of patching your "global" css and js (javascript) files everytime you can simply add the code to your MediaWiki:Common.js and MediaWiki:Common.css pages. As these are part of the database which will be reused when you upgrade, you will not have to patch the MediaWiki core files any more.

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?
Generally yes, however Git may temporarily (for a few seconds) break it.

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

Note: the following assumes you have command line access. 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) In the release notes for the new version, see if any changes need to be made to LocalSettings.php.
 * 4) Place the database in read-only mode by inserting the following variable into LocalSettings.php in the old directory - users will see this message if they attempt an edit during the upgrade process:
 * 5) Run the update script in the new directory.
 * 6) Copy the images from the images sub-directory from the old directory to the new directory.
 * 7) Swap the old directory and the new directory.

Why upgrade?
Many upgrades solve security issues which help to keep your wiki and possibly even your host system safe from vandals. New major releases come with new features, which you might want to use. See the release notes for details. In case you need additional arguments to convince your bosses to let you upgrade from a pretty old version:


 * As of MediaWiki 1.16, the user groups ACL system has an important improvement: you can now revoke rights.
 * As of 1.16, the new Vector skin looks nicer and is more moddable.
 * Performance improvements. If you have appropriate caching, ResourceLoader optimizes pageload speeds a lot.
 * Category sorting makes sense!
 * In MediaWiki 1.18 we started bundling some vital extensions, like a better editor and anti-vandalism tools ConfirmEdit and Nuke.
 * In MediaWiki 1.19 the skinning system was reworked making it easier to reuse parts of existing skins in your own skins.