WordPress 2.9 was recently released, and there were some huge improvements made — which I’m really excited about. But, as anyone may know, there’s always a bug…somewhere.

This time, it happened to be a failed upgrade process.

In brief, there were some database queries that shouldn’t have been added, but they were. So some people may experience memory exhaustion and won’t be able to upgrade. Fear not though! The WordPress 2.9.1 Beta will be available shortly, but as the post describes, you can user the beta tester plugin to grab the latest code before it’s officially released.

If you’re interested in the technical side of the bug, here is what happened:

As described in great detail by several frantic webmasters at http://wordpress.org/support/topic/342965

#2699 added a ridiculous SELECT then DELETE pattern to the upgrader, where only a DELETE was needed. As a result, the SELECT statement causes memory exhaustion and upgrade death.