VAC was unable to verify your game session

There was a very disruptive behavior seen by CS: GO where players would get the error “VAC was unable to verify your game session”. Hence the players are unable to queue for matchmaking and play any matches.

VAC is the Valve Anti-Cheat System. Its main job is detecting installation files anomalies where files might be manipulated to provide unfair means for players to gain an edge over other people. If you are getting this error even if you didn’t do anything wrong, it means there are problems with the configuration of the files. Start with the first solution and work your way down.

How to Fix VAC was unable to verify the game session Error?

1. Running Steam as Administrator

The first and foremost thing which we should check is if Steam has administrator access on your computer.

Steam requires full access in order to provide you with the optimal gaming experience. This means changing system configuration files and having a lot of resources and memory at its disposal. Be default, Steam doesn’t have full administrator access.

We can grant Steam full administrative privileges and check if the problem gets solved. First, we should make the changes to the Steam.exe file and later grant the whole Steam directory access as there are various configuration files present in the main directory.

2. Verifying integrity of game files and repairing library

Most of the games available in Steam are very huge files consisting of several GB’s. It is possible that during the download/update, some of the data may have been corrupted. Steam has a feature within the client itself where you can verify the integrity of game files quite easily.

This feature compares your downloaded game with that of the latest version present in the Steam servers. Once it is done crosschecking, it removes any unwanted files or updates them if needed. There are manifests present in each computer where a game is installed. Instead of checking the files one by one (which take hours), Steam compares the manifest present on your PC with the one in the servers. This way the process takes place much more quickly and efficiently.

We can also try repairing Steam Library files. Steam Library is the place where all your games are present and you can only access them through it. It is possible that your Steam library isn’t in the correct configuration. There may also be a case where you have installed Steam on one drive and your games are on another one. In that case, you have to repair both the libraries before launching your game again.

Do note that this process takes some times as a lot of computation is going on. Don’t cancel the process in between to avoid any further errors. Furthermore, Steam may ask you to enter your credentials once it is done with the process. Don’t follow this solution if you don’t have your account information at hand.

3. Repairing Steam Client

If both the above methods don’t work, there is also a chance that your Steam client is either corrupt or has some bad files present. We can fix this by executing a command on the command line. Do note that you might require administrator privileges to perform this solution.

1. Press Windows + S, type “cmd” in the dialogue box, right-click on the application and select “Run as administrator”.
2. Once in elevated command prompt, execute the following command:

"C:\Program Files (x86)\Steam\bin\SteamService.exe" /repair

Here the path located within the colons indicate the location of Steam on your computer. You can change this if Steam is located elsewhere.

3. Wait for the whole process to complete. Then restart your computer and check if this solved the problem at hand.

4. Power Cycling your Computer

If all the above methods don’t bear any fruit, we can try power cycling your system.

Power cycling is an act of turning off a computer completely off and then on again. Reasons for power cycling include having an electronic device reinitialize its set of configurations parameters or recover from an unresponsive state or module. It is also used to reset all the network configurations as they are all lost when you turn the laptop completely off.

To power cycle your laptop shut it down properly and remove all the wires from it. Next remove the battery properly and detach it. Press the Power button for 1 minute. Now, wait for around 2-3 minutes before plugging the battery back in. The reason for taking out the battery is to make sure that all the capacitors are discharged correctly and all the current data stored in RAM is lost. After turning the laptop back on, check if the problem got solved.

In case of a PC, shut it down completely, disconnect all modules and take out the main power cable. Now after waiting for the required time, plug everything back in and check if this solved the problem.

5. Ending Steam Service

In some cases, the steam service might already be running in the background and it might have been glitched due to which this error is being triggered. Therefore, in this step, we will be ending the steam service. In order to do so, follow the guide below.

1. Press “Windows” + “R” to open the Run prompt.
2. Type in “Taskmgr” and press “Enter”.

   

3. Click on the “Processes” tab and select “Steam Service” from it.
4. Click on the “End Task” button and close the task manager.

   

5. Check to see if the issue persists.

6. Copying DLL File

There are two steam service dll files located on your computer, one in the Program Files and the other one in the steam installation directory. In certain cases, these files might differ from each other due to which Steam is unable to verify your session. Therefore, in this step, we will be copying this DLL and replacing it with the other one. For that:

1. Open the steam installation directory, commonly it should be similar to the one below.

   C>Program Files (x86)> Steam > Bin

2. Now, right-click on the “Steamservice.dll” file and select the “Copy” option from the menu.

   

3. Now navigate to the following location.

   C>Program Files (x86)>Common Files> Steam

4. Paste the “.dll” file in here and select the “Replace” option if prompted.
5. Launch Steam and try to start the game that you are trying to play
6. Check to see if the issue persists.

7. Deleting Temporary Files

In certain cases, the temporary files that are being stored by the computer might have gotten corrupt over time due to which this error is being triggered. Therefore, in this step, we will be deleting these temporary files and then check if the error still persists.

1. Press “Windows” + “R” to open the Run prompt.
2. Type in “%temp%” and press “Enter”.

   

3. Press “CTRL” + “A” and press “Shift” + “Delete”.
4. Click on “Yes” in the prompt to delete all the temporary files.
5. Check to see if the issue still persists.

8. Performing a File Repair

In certain cases, the error is triggered if important steam library files are corrupted. Therefore, in this step, we will be performing a file repair. In order to do so, follow the steps listed below.

1. Press “Windows” + “R” to open the Run Prompt.

   

2. Type in the following command in this prompt.

   "C:\Program Files (x86)\Steam\bin\SteamService.exe" /repair

3. Let the repair run and check to see if the issue persists.
4. If the issue does exist, navigate to the following location.

   C:\Program Files (x86)\Steam\SteamApps\common\Counter-Strike Global Offensive\csgo\maps\workshop

5. Press “Ctrl” + “A” and delete everything inside the folder by pressing “Shift” + “Delete”.
6. After that, navigate to the following location.

   C:\Program Files (x86)\Steam\SteamApps\common\Counter-Strike Global Offensive\csgo\maps\graphs\workshop

7. Again, Press “Ctrl” + “A” to select everything inside this folder and then press “Shift” + “Delete” to remove it.
8. After doing so, run steam and let it download the missing files.
9. Check to see if the issue persists.
10. If the issue still persists, open the run prompt by pressing “Windows” + “R”.
11. Type in “Cmd” and press “Shift” + “Ctrl” + “Enter” to grant administrative privileges.

    

12. Type in the following commands and press “Enter” to execute them.

    start steam://flushconfig
    ipconfig /release
    ipconfig /renew

    

13. Now check if the issue is still present.
14. If you cannot get around the issue in any other way, type the following in your command prompt but beware that it disables some security features which let VAC through and the error is fixed.

    bcdedit.exe /set {current} nx OptIn

9. Checking for Background Services/Tasks

Virtualizations Softwares and other VPN/Proxies might be the root behind this issue because VAC can sometimes flag you if you are running any of these. Therefore, in this step, we will be stopping all of these Softwares from running in the background.

1. Press “Windows’ + “R” to open the Run prompt.
2. Type in “services.msc” and press “Enter” to run it.

   

3. In the service management window, right-click on any of the following services if you see them and select “Disable”.

   VMnetDHCP
   VMUSBArbService
   VMware NAT Service
   VMwareHostd
   VMAuthdService
   hshld

4. Now, open the Task Manager by pressing “Ctrl” + “Alt” + “Del” and then selecting “Task Manager”.

   

5. In the task manager, end the following processes if you see them.

   hydra.exe
   hsswd.exe
   hsscp.exe
   vmware.exe

6. After doing so, check to see if the issue persists.

10. Try Some General Fixes

In addition to the methods above, try the following steps to initiate some further troubleshooting.

1. You can try restarting your Steam client properly. Go to Steam, change your username, and exit the client by clicking Steam > Exit. Now open Steam again and go into Offline mode. Now go back online and check.
2. Make sure you don’t have any network anomalies and the network is running perfectly. Also, clear Steam, CS:GO and other games from the Firewall restrictions to make sure that they are not being blocked.
3. Check your antivirus software or any third-party program (such as CCleaner). They are known to conflict with Steam.
4. Try to reinstall DirectX, .NET Framework, Microsoft Redistributable and other important software.
5. Try to change your Profile name, close steam and check if that fixes the issue. If it does, you can change it back later.
6. If you have idle master, close it and restart your PC. Now, check if CSGO is working.
7. Try deleting your Config file or any keybinds that you might have set.
8. If all the above methods don’t work as expected, you can back up your data and reinstall Steam completely.

11. Turn off Steam Beta

In some cases, the Beta mode of Steam might be causing this issue. Therefore, in this step, we will be opting out of the beta program for Steam. In order to do so, follow the guide below.

1. Launch Steam and sign in to your account.
2. Click on the “Steam” option on the top left side and select “Settings” from the options.

   

3. Select “Account” in the left pane and click on the “Change” option below the Beta Participation setting.
4. Select the “None-Opt out of all Beta programs” option.

   

5. Save your settings and check to see if the issue persists.

12. Updating Windows

In certain cases, having an outdated version of Windows leaves your computer vulnerable to many risks and creates an opportunity for failure. Therefore, in this step, we will be initiating a Windows update and check to see if the issue still persists after updating Windows. For that:

1. Press “Windows” + “I” to open the settings.
2. Click on the “Update & Security” option and then select “Windows Update” from the left pane.
3. Click on the “Check for Updates” option and wait while Windows installs updates.

   

4. Check to see if the issue persists after updating your computer.