How to fix CS:GO VAC authentication error

Valve Anti-Cheat or VAC is there to prevent people from using third-party programs to gain an upper hand in certain games. However, you may get a VAC authentication error on CS:GO from time to time, preventing you from playing the game.

The Counter-Strike games have proven to be extremely popular over the years, but they aren't without flaws. And with CS:GO's focus on being an online multiplayer experience, you can expect error messages to pop up every once in a while.

In this article, we'll help you deal with the VAC authentication error if it's giving you a hard time, even though you're not using any sort of cheat software.

What is CS:GO VAC Authentication error?

The VAC (Valve Anti-Cheat) authentication error in CS:GO is an issue that occurs when the game's anti-cheat system fails to authenticate a player's game files or detects unauthorized modifications.

There are a number of causes that can be behind the VAC authentication error in CS:GO. One common reason behind this error is having Data Execution Prevention disabled on your computer.

Another cause for the authentication error is software conflicts. Running software such as CCleaner, IObit Start Menu 8, etc while playing can cause this error. Find the full list of conflicting software here.

Additionally, modifying game files and/or in-game textures may cause this error.

How to fix CS:GO VAC authentication error

The Steam support page suggests removing any custom textures, skin changers, or software that modifies game files and restarting your computer to fix CS:GO VAC authentication error.

They also recommend verifying your game files after making these changes. In case the issue persists, follow the troubleshooting tips listed below.

Repair Steam Service

Follow these steps to try and repair Steam Service to get rid of the VAC authentication error:

• Find the root folder of your Steam installation. You can do this by right-clicking on the Steam shortcut and selecting "Open file location".
• Click on the address bar at the top and copy the file path, it should be C:\Program Files (x86)\Steam\bin\SteamService.exe unless you've installed Steam on a different drive.
• Search for your Command Prompt and run it as an administrator.
• Type in the command: "C:\Program Files (x86)\Steam\bin\SteamService.exe" /repair

You can then try opening CS:GO again to see if the authentication error still persists.

Restore boot settings to default

Here's what you can try if you think the Data Execution Prevention settings are behind the error:

• Exit Steam
• Search for your Command Prompt and run it as an administrator.
• Type in the following commands, pressing Enter after each one:
  • bcdedit /deletevalue nointegritychecks
  • bcdedit /deletevalue loadoptions
  • bcdedit /debug off
  • bcdedit /deletevalue nx
• Restart your computer.
• Launch steam.

From there you can try starting up CS:GO again to see if you still get the error message.

Repair system files

Corrupt files can also be the cause behind the CS:GO VAC authentication error. Here's how you can repair them:

• Exit Steam.
• Search for Command Prompt and run it as an administrator.
• Type the command sfc /scannow then press Enter.
• Wait for the process to complete then restart your computer.

Once your PC has booted back up, you can test to see if the error has stopped showing up.

If you've tried everything listed above but the error is still popping up, you may want to contact Steam support.