Same...unable to login. Same message upon entering password and id. What exactly "account maintenance"? They are doing that this morning. Perhaps that is either due to these errors or causing these errors??
Just tried to log in after not playing for a few days. Once the game loads to the login screen, it throws up an error saying that it could not log in through Steam.
This thread started because of a brief hiccup when ZOS did the account maintenance a few days back. If you are having a different issue, you might start your own thread.