Error 1B: your ISP is getting in the way of the login
League clientLoginRiot's name for this error
League of Legends Error 1BWhat it means
A connection problem between your internet provider and League's servers is stopping the login. Riot says it usually sorts itself out in a couple of hours.
What to try first
Run the League client as administrator and try again. Otherwise, give it an hour or two.
Is it you or Riot? If lots of players are hitting this at once, it's probably the servers. Check League server status before you start reinstalling things.
What Riot says about 1B
Riot's League error table gives 1B two lines. The error keeps you from logging in, and Riot puts the cause with internet providers: something on the ISP's end is disrupting your connection to League's servers.
That makes it different from Error 7, where Riot's own servers are the ones struggling. With 1B the servers can be fine and you still can't get through.
How to fix it
Riot's one suggestion is to launch the League client in administrator mode, on PC. Right-click the shortcut, choose Run as administrator, and log in from there.
If that changes nothing, Riot's advice amounts to waiting. The table says 1B is known to fix itself within a couple of hours. It's still worth a quick look at League server status so you know which side you're waiting on.
Other wordings of the same error
Error 1BError code 1BLoL error 1BLeague error 1b
Related errors
Source: Riot Games Player Support, League Error Codes and Solutions, updated May 19, 2025. Riot's steps are paraphrased here, not copied; checked September 25, 2026.