Much like installing MediaWiki, upgrading MediaWiki is generally pretty easy, and follows much the same process. The installation script checks to see if there is already a MediaWiki database at the location you specify, and will upgrade it rather than installing a new one if it detects it.
Of course, it is always highly recommended to back up your database and existing files before doing anything; that way if you get stuck, you have a working version to revert to.
The largest version-span I've ever tried to do was upgrading MW 1.4.4 to 1.7.1; amazingly enough, it worked almost without a hitch; the only broken part was that the login page would not work – I got the following message instead of a proper page:
- Fatal error: Cannot access parent:: when no class scope is active in :/hsphere/local/home/hypertwi/wiki.sluggysquad.com/includes/SkinTemplate.php on line 108
After googling for bits of the error message and not getting any matches, then poring through PHP documentation trying to understand what was going on, I finally (in semi-desperation, and mainly because #wikimedia-tech was engaged in a conversation which I didn't want to interrupt) simply commented out line 108:
- // parent::initPage( $out );
...and the login page magically started working. I'm sure there will be a price to pay somewhere, but if so I'll make a note here when I find it. --Woozle 10:16, 23 August 2006 (EDT)