In short: We have to update the account system so we can launch new games. When this update takes effect, it’ll cause problems for players with login names that aren’t globally unique (aka, someone else in another region has it as well), so we’re asking players with duplicate usernames to change them. This only affects the username you use to sign into League. Your Summoner Name will not be affected.

The long version: In preparation for launching new games, we need to rebuild our account system. The old system linked accounts to specific regions, meaning we couldn’t release another game unless it has the same exact regional divisions as League of Legends. This is problematic as we might offer different regional configurations for future games.

In order to fix this, every player needs a unique username, and there’s currently a lot of duplication across servers. As long as there are two people with the same username, neither will be able to log in when we activate the unique username system. We tried to find a way to make the system work differently, but couldn’t find a solution that would be reliable, secure, and sustainable for a multi-game platform.

We wish this transition were less painful and inconvenient. We know it sucks to have to change a piece of your identity as a player, even if it’s one that only you can see. We’re asking players to change how they log in now—before the unique username system activates—so everyone’s experience with future games is as smooth as possible. We know this process hasn’t met your expectations, and frankly, it hasn’t met ours either. We’re working hard to make sure our new systems are as future-proof as possible to avoid situations like this down the line.

In the meantime, we hope that being able to save your username and password to auto-login will make things a little easier. We’re also exploring allowing you to log in with your email address instead of your username, which we’ve seen a lot of players ask for. And for anyone who’s unhappy with the username they changed to, we’re planning on letting you change your login credentials again early next year.