Just found a solution: deactivate all the plugines and then do the upgrade. Everything went through fine.
I have exactly the same problem. I was running 2.8.1-beta2
I guess the reason the htaccess at the root directory doesn’t cover /wordpress is because there is a htaccess file at /wordpress?
I moved the rule to the top of .htaccess in /wordpress and it works! Thank you very much!
