are you able to login to your account itself?
not at support portal but at main account site or ingame
Won't be able to check for awhile here, will post an update when I am able to.
*Edit*
Tested the account login on the main page so the credentials are working correctly. Would assume the game is the same. Looks like it definitely is the support portal.
I can log into the game and forum (obviously) but can't log-in to support. I've tried using an old password, ive tried copying and pasting the exact same username and password, pasting into account login and support login. Account lets me login perfectly fine but support repeatedly gives me authentication error.
From what i've seen this is a common error that ZOS have tried to fix before but just keeps creeping back.
I've managed to gain access to the support page and i have a fix that may work for someone with the same issue.
The issue i was having was that the password box for the support page only accepts 20 characters, so if you have a password with more than 20 characters, then the rest of your password is cut off.
If you try changing your password to something that has 20 characters or less, it might fix the issue