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League of Legends error

Unsupported operating system: League doesn't recognize your Windows version

League clientWindows

Riot's name for this error

You are on an unsupported operating system

What it means

The game has decided your version of Windows isn't one it supports, so it won't let you in.

What to try first

Right-click the game's .exe, open Properties, then Compatibility, and untick Run this program in compatibility mode for. If that box was already clear, update Windows.

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.

Two ways to get this

Riot's article (it covers every Riot game) says this appears when the game sees a Windows version it doesn't support. There are two routes there, and the fixes match them.

The first is the obvious one: your Windows really is older than the game supports. The second is a setting on the game itself. Windows can run any program in compatibility mode for an older version of Windows, picked from a dropdown on the program's Compatibility tab, and Riot has you make sure that's switched off on the game's .exe. It's easy to miss if someone ticked it months ago.

Riot's article doesn't print the full text of the error box, so the line above is the article's own title.

How to fix it

  1. Check your Windows version against the game's requirements. Riot links a requirements page for each game (League and TFT share one, and VALORANT, Legends of Runeterra and 2XKO get their own). If you're below the minimum, update Windows to the newest version you can get.
  2. Turn off compatibility mode. Right-click the game's .exe, open Properties, then Compatibility. Untick Run this program in compatibility mode for, click Apply and OK, and launch again.

That Compatibility tab turns up in Riot's League guides for games that won't load after champion select too, where Riot has you clear its boxes (see stuck at reconnect after champion select).

Other wordings of the same error

  • Unsupported operating system League
  • League of Legends unsupported OS

Source: Riot Games Player Support, How to Fix Error "You are on an unsupported Operating System", updated May 23, 2026. Riot's steps are paraphrased here, not copied; checked September 25, 2026.