Error code

Steam 80

STEAM80
Game/Platform Error· An error code shown by a game or gaming platform/launcher.

What it means

A game fails to launch — displays "Error Code: 80" or "Failed to start game (app already running)"..

How to fix it

  1. Verify integrity of game files (right-click game > Properties > Installed Files).
  2. Run Steam as administrator.
  3. Check that the Steam library folder is not set to read-only.
  4. Clear the Steam download cache in Settings > Downloads.
  5. Disable antivirus temporarily.
  6. Reinstall Steam as a last resort.

Not affiliated with Steam. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.