Fix WordPress upgrade error: No Update Required -Your WordPress database is already up-to-date!

I recently upgraded my blog to WordPress 3.x and everything seemed to go smoothly with the process. But after upgraded when I go to the WordPress admin, I still get the upgrade page, and message show like:
No Upgrade Required
Your WordPress database is already up-to-date!
When I clicking the “Continue” button it sent into a loop.
After much troubleshooting, the solution for fix the “No Update Required –Your WordPress database is already up-to-date!” looping. I have re-upload all files & folders except the wp-content folder from a fresh download of WordPress.
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I just came across this after an update – traced it to the memcache object cache plugin. The update does not clear its own cached objects.
I have numerous live sites on my server, so restarting memcached is not an option, as users would be forced to log in again.
I just changed the cache keys so that new objects would be cached under a different name – the old ones will expire or disappear at next kernel update when I reboot the servers.
Alternatively, just rename wp-content/object-cache.php temporarily to continue admin.
I have a suggestion for the author of wp-content/object-cache.php, DB_NAME needs adding to the key, otherwise the caches of users using “wp_” prefix on different databases will clash.
I had the same problem. I rename the object-cache.php and the site works fine. Later i discover that the W3 Total Cache plugin was the problem. I delet it and my site still work fine.