Thread:Project:Support desk/Problem upgrading Mediawiki 1.5.8 to Mediawiki 1.19 (libxml2 inadequate on server)

I have a wiki set up on my local development environment (PHP 5.2.9, MySQL 5.1.33). The wiki runs on Mediawiki 1.5.8, but I'm trying to upgrade it to run on Mediawiki 1.19.

When I run the update.php script I get the following error message:

I've got libxml2 insalled via MacPorts, and according to MacPorts version 2.7.8 is installed, which should be sufficiently up-to-date to get Mediawiki updating properly.

Any ideas as to how I can go about resolving this?