Some times this error occurs when a player is unable to reach one of the game's megaservers. If you receive this error, you should try again in a few minutes. If you continue to receive this message after waiting, you can attempt the following steps:
Make sure that any anti-virus/firewall protection has exception rules for The Elder Scrolls Online.
Make sure the following ports are open on the networking device:
TCP / UDP Ports 24100 through 24131
TCP / UDP Ports 24300 through 24331
TCP / UDP Ports 24500 through 24507
TCP Port 80
TCP Port 433
Check our Service Alerts page for details about the status of the game.
If you need help with performing these actions, have further questions, or have completed these steps and are still experiencing the issue, you should feel free to contact our dedicated Customer Support team for assistance.
The Elder Scrolls Online: Tamriel Unlimited - ZeniMax Online Studios