Steam error 51 - how to fix it

Steam error 51 can in rare cases prevent a game from starting. Here's how to fix the annoying error.

How to fix Steam error 51

Steam error 51 (error code 51) can have different causes. In most cases, however, it triggers applications running in the background. In particular, the tools "Airfoil" and "F-Secure" are related to the error:

• If you are using an older version of Airfoil, deactivate the "Instant Hijack" function in the program settings. The error should no longer occur in connection with newer program versions.
• F-Secure users should deactivate the "DeepGuard" feature.
• There are also a number of other programs that can disrupt Steam. This primarily includes virus scanners, anti-spyware tools and firewalls. Valve has summarized an overview of known programs here. You should deactivate or uninstall corresponding programs as a test.
• The ClientRegistry.blob file may also be corrupted. You can find it in the Steam installation directory and you can delete it without hesitation, since in this case it will be automatically recreated.
• Defective game data can also be responsible for Steam error 51. Right-click on the affected game in the Steam client and then on "Settings". Then select the "Check game data for errors ..." option in the "Local files" tab. Steam automatically downloads corrupted files and fixes the bugs.
• Some graphics card drivers can also trigger Steam error 51. If you have recently carried out a driver update, you can try whether the error no longer occurs with a different driver version.

Another practical tip shows you what you can do with Steam error code 80.