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League of Legends error

"We've detected a problem with your installation": League needs a repair

League clientRepair

The message

Sorry! We've detected a problem with your installation. Repair will now attempt to restore the required files.

What it means

League has spotted files it needs that are missing or damaged, and it's offering to put them back. Usually the repair runs on its own after you click through.

What to try first

Let the repair run. If nothing happens, do a clean boot, delete the Riot Games folder in %localappdata%, then start the repair from the Riot Client's League settings.

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.

When the repair doesn't kick in

Click through and the repair usually starts by itself. Sometimes it doesn't. Riot files this under the known issues for its updated client (that page was last revised June 1, 2026) and gives a short routine for a repair that never begins.

  1. Clean boot first. You want nothing from Riot or League running in the background for the next two steps (Riot's clean boot guide is linked below).
  2. Clear the local Riot folder. Press Win+R, enter %localappdata%, and delete the whole Riot Games folder in there.
  3. Start the repair yourself. In the Riot Client, your profile icon sits in the top right corner. Click it, go to Settings, pick League of Legends, and hit Start Repair.

Riot's guide: Perform a clean boot

Did the repair start and then error out? That's a separate problem with its own checklist: full client repair failed.

Crashing after a reinstall

Plenty of people answer this message by reinstalling League. Riot warns against doing that halfway. Its updated client and the legacy client use some of the same files (a detail that's easy to miss), which means removing one of them affects the other, and the game can start crashing more often afterward.

The cure is a bit drastic. Strip every League file off the PC, then install fresh.

Other wordings of the same error

  • We've detected a problem with your installation
  • League detected a problem with your installation
  • Repair will now attempt to restore the required files

Source: Riot Games Player Support, Updated Client - Known Issues, updated June 1, 2026. Riot's steps are paraphrased here, not copied; checked September 29, 2026.