I recently upgraded my blog software to WordPress 2.1 via the DreamHost one-click installer (an awesome service!), just to get improvements and bugfixes. It ran well for a while until some time Tuesday. I noticed the problem when I attempted to enter some comments at various other blogs, referencing some of my posts, and needing to look up the permalinks. To my surprise, I couldn’t open them. And I couldn’t open the main website either.
I wrote up a support ticket with DreamHost and got a reply back mentioning something about too much memory being used by my site and that this is usually due to badly written plug-ins.
So I dug around the log files, searched the DreamHost support area, searched the WordPress support area and finally typed this into Google: “WordPress 2.1 internal server error”. That led me to http://www.quickonlinetips.com/archives/2006/12/site-down-36-hours-how-i-fixed-internal-server-errors/. There I found a description of exactly the same problem, and how it was solved by restoring the default configuration for wp-cache and then leaving it turned off. That’s what I did, and now the blog is back up and running again.
I never suspected wp-cache to be the culprit, especially since DreamHost encourages you to turn it on right away after installing WordPress to improve performance. I think this is something that should be looked into, DreamHost!