Maintenance for the week of October 5:
• [COMPLETE] ESO Store and Account System for maintenance – October 8, 8:00AM EDT (12:00 UTC) – 12:00PM EDT (16:00 UTC)
Go into Documents => Elder Scrolls Online => Live.
Delete or rename User-Settings.txt.
Relaunch game. Should be able to log in, or port into zone.
Not sure why the user-settings.txt causes the issue.. but it does. Also, deleting it or removing it won't hurt anything or change keybinds or stuff like that. It'll create a new one when you relaunch.