http://wordpress.org/support/topic/217792?replies=4 THIS is what I needed to do!
Did you disable plugins? If not backup your wp-contents/plugins folder, then rename it to wp-content/plugins_old, then create a emplty folder called plugins. Then try the upgrade.
Hi all,
I am having the same issue on my blog http://littlelioness.net after upgrading from 2.6 to 2.6.3 (at least that’s what I THOUGHT Id downloaded from the .org site, though the readme has it as 2.6.1)
I have reset my password, cleared cache etc etc.
Yes, I forgot to disable my plugins (but that’s a bit late now, hey?)
Any ideas? Delete and reinstall?