I had the same problem after upgrading and
Make sure that you’re defining the SECRET_KEY before the require_once line for wp-config. Put it before the “That’s all, stop editing!” line (typically line 18) and you’ll be good to go!
did solve the problem.
Thanks ecaron.
It should not be Firefox-related – i am using Firefox 3 since yesterday and the problem was solved with simply putting the SECRET_KEY on the correct place.
i had the same problem (not with upgrade, but clean install).
the problem was solved by removing a line-break in the file functions.php in the wp-includes folder.
it was after the closing ?> tag. when i removed it the installation worked perfectly fine!
