Steam – “VAC was unable to verify the game session”

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It's CS:GO, and the error reads as the title. Now, your first thought may probably be "can this dude even use Google?", but I've been unable to solve this issue for three days now.

I have tried the following potential solutions:

  • Restart CS:GO
  • Restart Steam
  • Log out / log in to Steam
  • Restart computer
  • Verify integrity of game files (also tried restarting the computer before it re-obtained the file)
  • Run C:\Program Files (x86)\Steam\bin\steamservice.exe" /repair.
  • Remove local files and re-install the game fully from scratch
  • Restart router

Also, the last update where the Panorama UI was released out of beta was released yesterday, so the game has auto-updated into a verifiably new version since the problem started occurring.

None of the above things have worked, and I've tried them multiple times over the last three days, without any success.

If it means anything, I have 3052 hours in-game and no previous VAC bans or other account anomalies.

Any help is greatly appreciated. Thank you!

EDIT
My problem has finally resolved itself. I don't know the exact cause, but I have a theory.

The problem started when I opted in to the beta of the Panorama UI and then tried to play a game on official servers. This required me to opt-out of the beta, which I did. The problem then started.

It remained until the second update after the Panorama UI was officially released. After updating at that time, the problem vanished. I believe there was simply something corrupt in my game system after opting into the beta which was overwritten by that update the fixed the system. I won't write this as an answer, because I don't really know what solved the issue, but after this, the problem went away.

Happy gaming!

Best Answer

There have been many different suggested solutions in the Steam forums for this exact issue, and some of the solutions seem to have worked for a minor subset of the users facing this problem. I'm sure you've been through those forums and tried every sensible suggestion. Just like myself. In my case, however, none of the solutions did work. The problem I was having was that I was using the same computer for both playing CS:GO, and my software development work. I had tons of development tools installed, and some of the stuff I had installed was somehow hooking into the game process, or otherwise running in the background and being picked up by the useless and incompetent tool we call VAC.

This particular message is displayed when VAC cannot verify your game installation (the files, or the running process) for whatever reason, or when it detects a suspicious process in the background from its own weird perspective. It doesn't detect a cheat per se, but it just detects that there's some kind of modification going on, or a suspected modification that it deems as possibly going on.

At first, I used to format the PC and install everything from scratch, and it used to work for a while. But eventually I would start getting the same issue. Basically in order to resolve it for good, I've started using a separate PC for gaming, and never had the same problem again. (It's been years.)

I realize this isn't the ideal solution you're looking for, but your case might be similar... Some software development tools hooking into other processes, some badly designed driver the game is accessing, the antivirus software being way too eager than it should, a virus or a trojan... I've even met someone who had the very same issue just because he had a PowerShell update installed on the machine.

What you can try before going into extremes is:

  1. Make sure your antivirus software (I am simply assuming there is one installed) is up to date, and perform a full scan.
  2. If nothing shows up, pick a few well known alternative antivirus suits, and install them with their trial licenses one by one, performing a full system scan with each one of them. These first 2 steps are just to insure there's no virus/malware messing with your system.
  3. Check which applications are running on startup via the settings or the task manager. You can disable anything that you don't actually need.
  4. If that doesn't work, try disabling everything, and give it a try. If you're good, then try enabling them one by one in order to find out which particular application is causing the issue.
  5. If that doesn't help, you may wanna try checking out what's starting at boot or login time via CCleaner. And if it shows up any extra applications, you can try the same steps usinc CCleaner as well.
  6. Still no luck? One last option you might try is uninstalling every single application completely, apart from Steam and drivers. Take a note of the applications you've just uninstalled. If this actually works, you may want to install them in order of actual necessity, one by one, and check if that particular one is the problematic app.

If none of the above helps you, I'm afraid you're gonna need a clean installation of windows. Of course, having a PC just for gaming isn't something everyone would be willing to or able to fork out some extra cash for. But you might want to try having 2 separate Windows installations on the same machine, one for just gaming, one for everything else. That would greatly reduce the risk of experiencing the same issue in the future.

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