I’ve setup my wordpress so it does object caching. This improves performance but is a pain when you have to upgrade your system. After the latest WP 3.0 -> WP 3.0.1 upgrade via automatic upgrade I noticed that I was stuck at the upgrade page saying that I didn’t need to upgrade my database and with the OK button redirecting me to my frontpage. Well, this is all good and all, but I wanted to go into my admin section, not my front page. There was a cache problem in wordpress. After fiddling around the only thing that manage to solve the problem was to delete the cache folder and rebuild it again.
So, If you’re experiencing some post upgrade wordpress problems and you’re using some sort of caching mechanism…
Delete the /cache folder at /wp-content
And while I was loosing my time trying to figure out why was I locked out of my WordPress admin pages, the website was running because I had the UNIVERSAL CACHING MECHANISM FOR WORDPRESS: static files