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 later than 5.1.0, apart from 5.3.1 which has a serious bug which renders it incompatible with MediaWiki.

PHP 5.0 has broad compatibility with current versions, but it is not actively supported and will deteriorate over time. PHP 5.0 has known issues with array functions on 64-bit systems, and is explicitly incompatible on those operating systems.

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).

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 classes exist have at least some support.

Web server
MediaWiki is broadly compatible with all major web servers that can invoke PHP. Compatibility is strongest for Apache and IIS.

Browser
All current major web browsers are compatible with most versions of MediaWiki. Compatibility is maintained for legacy versions of web browsers until they fall to a sufficiently low level of utilisation. In particular, compatibility is currently maintained for Internet Explorer 6+, Firefox 2.0+, Safari 525+, Opera 10.0+, and Chrome 5.0+.

Browsers which are not explicitly marked as incompatible are often generally compatible. Support is not guaranteed for old non-standards compatible browsers and issues with those browsers might not be resolved.

CSS
MediaWiki is compatible with user agents which do not process CSS3 markup. Some additional features are available to browsers which can process these styles.

JavaScript
MediaWiki is accessible to user agents which do not process JavaScript. MediaWiki degrades gracefully and all essential functionality works without JavaScript, although some things might be less convenient.

Text-only browsers
MediaWiki is accessible to text-only user agents such as Lynx, and to interpreters such as JAWS. Some functionality is reduced.