Thread:Project:Support desk/How to Upgrade MediaWiki 1.12 to 1.24/reply

First, you should upgrade your webserver system. PHP 5.1.6 is really old and the support for it was stopped in MediaWiki 1.16 (which is stopped, too, and may contain security holes like your actual version), see Compatibility. The support for this php version was already stopped by php, too, see (eol 8 years ago now: http://php.net/eol.php). After this, you can follow Manual:Upgrade to upgrade your installation, but read the complete document first before you start your work, there are important notices about how to upgrade from an old version of MediaWiki. And the most important thing: Backups, backups, backups :)