Before starting TERA the game launcher requests a list of servers. If the launcher can't get that list you'll get Error: 0111:0001 after pressing Play.
Often this issue is fixed by pressing play again. If that doesn't work, try these steps.
Check the server status
If the TERA servers are currently down you may see Error 0111:0001 when pressing play. Check our server status.
Restarting your computer can resolve many technical issues and a great first step for troubleshooting many issues.
Check for connection issues
Temporarily losing your internet connection will mean that our launcher can't reach the servers. Check that you can access the internet and have the correct ports open. If you freqeuntly get connection issues, check out our Troubleshooting: Connectivity guide.
Repair your game
If you continue to have issues try repairing your game.