Fix for WordPress 3.0 Upgrade Hanging/Looping
We recently upgraded to WordPress 3.0 and everything seemed to have gone very smoothly with the process. After upgrading all the files, we ran the upgrade script, http://domain.com/wp-admin/upgrade.php. This confirmed that our database had been updated and clicking Continue took us to our home page.
There was only one problem – when we tried to go to the WordPress admin, we continued to get the upgrade script page asking us to upgrade. Clicking this button sent us into a loop. We kept getting this message:
No Upgrade Required
Your WordPress database is already up-to-date!
It was hanging there and not letting us into our admin section.
After much troubleshooting, it turns out the problem was not with our WordPress install at all, but rather with PHP-FPM caching. We restarted the php-fpm process (/etc/init.d/php-fpm restart) and everything started working perfectly. We also restarted the web server for good measure.