Compatibility

MediaWiki strives to maintain broad compatibility between versions, and with a range of current and legacy software. At the same time, the constantly-evolving codebase and features of the latest MediaWiki development mean that it is not possible to maintain compatibility with legacy software indefinitely.

PHP
The latest version of MediaWiki runs on any version of PHP to PHP 5.4. At this time, PHP 5.5 and greater have unresoved issues and might cause some functions to break.

The latest versions of MediaWiki contain features which are not supported by PHP 5.0, 5.1 and 5.2; attempts to run with these versions will fail.

PHP 4 is unsupported since MediaWiki 1.7, and attempts to run it will fail. If you are unable to upgrade your environment to PHP 5, you must use MW 1.6; note that this release has security issues and is no longer supported by the MW community (neither is PHP 4 supported by the PHP one).

MediaWiki 1.18 and later may additionally target the hiphop>Special:MyLanguage/HipHop|HipHop compiler, which will impose a few additional constraints on compatibility and coding style.

Database
MediaWiki is compatible with a variety of database servers, although support is strongest for MySQL.

Support for any other database software ranges from dubious to stable; architectures for which have at least some support. Anything other than MySQL is not recommended for production use at this point.

Web server
MediaWiki is broadly compatible with all major web servers that can invoke PHP. Compatibility is strongest for Apache and IIS. So long as the webserver version supports the required PHP version based on the matrix outlined here.

Software for using MediaWiki
Such information is no longer compiled. The general recommendation is to use decent as well as recent clients to work with MediaWiki. Historical information on this is available at software>Compatibility/Software for using MediaWiki|Compatibility/Software for using MediaWiki.