MediaWiki 1.27

MediaWiki 1.27 is a legacy release of MediaWiki. Consult the  file for the full list of changes. It was deployed on Wikimedia Foundation wikis through incremental "1.27.0-wmf.NN" branches from 29 September 2015 to March 2016 (1>Special:PrefixIndex//wmf|see details of each branch). The 1.27.0 stable release came out on 28 June 2016, and was a Long Term Support release (LTS) which was supported for three years until June 2019. Download the [https://releases.wikimedia.org/mediawiki/1.27/ latest releases] or checkout the   branch 2>Special:MyLanguage/Download from Git|in Git to follow this release.

InstantCommons made easier and cheaper
will now truly work out of the box, as long as your users can connect to upload.wikimedia.org: thumbnails will be served from that domain instead of requiring local generation (251556).

More documentation translation
Works continues on the migration to the Translate extension, now used by about 3000 pages. The size of translations text increased by various megabytes. Thanks go to our tireless translation administrators and translators but also to Google Code-in 2015 students, in particular IoannisKydonis who migrated thousands of translations including the entire Manual:FAQ.

Breaking changes

 * MediaWiki now requires at least PHP 5.5.9. This corresponds with HHVM 3.1.
 * The mbstring PHP extension is now required.
 * If the  and   PHP extensions are both unavailable, secure session storage (used for login) will raise an exception. This exception may be bypassed by setting  . Note that this bypass is not recommended. It is insecure. You should not use it.
 * After doing the upgrade, many users have problems with pages, which do not appear in their categories although they in fact are categorized correctly. In many cases this is a problem with the job queue.  The issue people usually have is that pages do not (in fact: not immediately) appear inside their categories.  Reasons may be different: It is possible that the job queue is not working correctly anymore.  Please read  and follow the advice given there in order to solve this issue.
 * The RandomRootPage extension has been merged into MediaWiki core. If you have it installed, you should uninstall it.
 * The ApiSandbox extension has been merged into MediaWiki core. If you have it installed, you should uninstall it.
 *   is deprecated and always true, and thus sessions are no longer stored using PHP's session handling (e.g. ). If you see issues with loss of session data while logging in, ensure you have a persistent shared cache configured for session storage in <tvar|SessionCacheType> </>.
 * AuthManager. If you're writing a new extension, you should definitely follow Manual:SessionManager and AuthManager and then upgrade to 1.27 to use it. If you are making sure an existing extension is compatible with 1.27, see the updating tips.

Release schedule
The dates for point releases for 1.27 were as follows: