Error code

Steam 6

STEAM6
Game/Platform Error· An error code shown by a game or gaming platform/launcher.

What it means

The Steam client logs out with "You have been logged on from another location" — corresponding to EResult 6 (LoggedInElsewhere)..

How to fix it

  1. Sign out of all other Steam sessions via Steam > Settings > Account > Manage Steam Guard.
  2. Change your Steam password if unauthorized access is suspected.
  3. Enable Steam Guard two-factor authentication.

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