A couple of days ago I upgraded my wordpress from 3.5.1 to 3.5.2. After the upgrade I wasn’t able to log back into the admin page. I just now got it back to working status. I found a post on the wordpress.org forum that helped me out. Thank you ahiddleston.
– V3.5.2 seemed to update okay but I was kicked out of the dashboard right after it finished patching
– could not get back in
– noticed the 404 URL string was referencing “wp-admin/upgrade.php” could not be found
– copied in a new and fresh upgrade.php file
– WordPress prompted that the DB was out of date and need patching
– DB patched — everything working great again.