Lots of people are reporting issues with their MySQL database version (MySQL is the database used to store all of your wordpress blog info – posts, comments, and so on). The new wordpress requires at least version 4.1.2 of MySQL, so if your version is older than this, you’ll need to upgrade MySQL too. Unless you’re familiar with your MySQL setup, you probably won’t see a problem until you try to run the 1-click wordpress upgrade – something like this:

“ERROR: WordPress 2.9 requires MySQL 4.1.2 or higher”

This is definitely out of the 1-click upgrade territory now so if you’re planning to tackle your upgrade I’d recommend making a couple of hours available.

Don Campbell wrote a nice overview recently of the steps that you need to go through to upgrade your MySQL database. Essentially you’ll need to create a brand new MySQL database using version 5, export all the data from your old database, and then read it back into the new one. It all seems like a lot of work but there doesn’t really seem to be an alternative. I’d highly recommend making a backup of your old database first – there’s a nice tutorial from wordpress and you’ll be doing this as part of the export process anyway.

OK, it’s not exactly pain-free but it certainly works (I’ve tried it on several wordpress installations) and it’s a nice way to spend New Year’s Eve. Happy upgrading!