Weird, I had the same error and it was solved by remaking the clientregistry.blob file. What have you tried so far? Here are some options. Order doesn't matter... probably. 1. Delete both blob files (the remade one and backup) Steam must be closed entirely for this, then restart. 2. Go into offline mode, then back online. 3. Right click the game, go to properties and opt into the beta, then try installing it. 4. Restart your PC 5. Wait an hour, then try again. 6. Wait a day, then try again. 7. Reinstall Steam 8. Reinstall Windows 9. Buy a new PC X. Buy a gun