"You do not have a valid Diablo III profile. (Error 316921)"
Screenshot : http://i.imgur.com/ypbLm.jpg
I can play the game fine, I can check some other friends profile (while others have the same problem), no problem accessing the AH or my own profile and achievements.
I checked the options, account settings, still am on the Americas region (never changed that ever), saved, but still have the bug.
I logged out and logged back in, same deal.
I exited Diablo 3, relaunched the game, same deal.