There has been notified that Steam has been showing an error, namely “Matchmaking: VAC was unable to verify the game session,” mostly for the CS GO game.
This has prevented the players from queuing for the match and playing any matches.
Fix VAC Was Unable To Verify The Game Session
For your food for thought, VAC is Valve Anti-Cheat System. The job of VAC is to detect any anomalies in the installation files that might be providing any edge to players through unfair means. If you got this error, this doesn’t mean you did something wrong. There might be a problem with your file configuration.
Many users have solved this problem with small tweaks. You can also do it, just follow the solutions given below one by one to be able to play your favorite CS GO game again.
#1 – Verify Integrity Of Game Files And Restart
Mostly, the games you download on Steam are very large, i.e., in GBs. So, there is a possibility that while downloading, a file may go missing or corrupted. But, Steam has a special option for that, through which you can check the integrity of the game file and fix it.
You must be wondering how does Steam do that? Well, Steam compares the downloaded game on your PC with the latest version of the same game on Steam servers. If there are any unwanted files, Steam removes them. And, if there are any broken or missing files, Steam updates those.
Checking each and every game file would be very time consuming and impractical. Therefore, there are manifests present along with the downloaded game, so Steam verifies the manifests instead of all game files. This process is much quicker and efficient.
Now, to verify the game files’ integrity, follow the steps given below:
- Firstly, run Steam client on your PC
- Now, go to the Steam Library tab.
- Then, right-click the game you want to verify and select “Properties” from the drop-down
- Once the properties window opens, go to the “local files tab”.
- Here, you’ll find an option “Verify Integrity of Game Files”, click that
- Now, Steam will start verifying the game files. This might take some time, so have some patience.
- Once the process ends, restart your computer.
After the restart, rerun your game to check, “VAC was unable to verify the game session” error is gone or not. If not, then jump to the next solution.
#2 – Restart Steam Client
There is a possibility that the problem is with the Steam client itself. Probably the steam client didn’t launch properly. Therefore, it is better to restart or relaunch your steam client to avoid this error.
Here are the steps you can follow to restart your steam client properly:
- Firstly, go to the Steam client and locate the “Steam” option on the left corner of the screen. Click it.
- Now select the ”exit” option from the drop-down to close the steam client completely.
- Open the steam client again and go to the “Steam” option. From the drop-down, select “Go offline” option.
- A popup window will appear, click the “Restart in offline mode” button in it.
- Now go to Steam option again, and select “Go online” from the list
- Click “Restart and Go Online” button appearing on the window
- Now, relaunch the game you are trying to play and check if you still get the error.
#3 – Repair Steam Client
If your luck didn’t work with the above two methods, then there might be some problem with your Steam client itself. It might be corrupted or some troublesome files present. This can be easily repaired through the command prompt. However, do make sure you have administrative privileges before trying out this solution.
To repair the Steam client, go through the steps given below:
- Go to the Window Search option located at the bottom left of the screen or press Windows + S key to open it directly
- Now, type “cmd” in the search bar and right-click the command prompt icon. Select “run as administrator” from the drop-down menu
- Once the command prompt opens in the elevated mode, type the following command:
- “C:\Program Files (x86)\Steam\bin\SteamService.exe” /repair
- The path given in the quotations is the path for the Steam client. However, make sure to change the path if your steam client is located somewhere else.
- Now, wait and let the process end. Once the process of repairing is complete, restart your PC.
#4 – Run Steam As Administrator
For optimal gaming performance, Steam demands full administrative privileges. Therefore, first of all, check if your Steam has full administrative privileges or not.
By default, Steam doesn’t have administrative access, and you have to give the access manually. To do so, follow these steps:
- First of all, go to the steam directory. The default location for the Steam installation folder is C:\Program Files (x86)\Steam. However, if you have installed Steam somewhere else, browse to that location.
- Now, in the Steam directory, find the steam.exe file. Right-click this file and select “properties” from the drop-down menu.
- Go to the compatibility tab in the properties windows. In the compatibility tab, check the checkbox named as “Run this program as an administrator”. Then save changes and close the window.
- Repeat the same with the GameOverlayUI.exe file and check the checkbox of “Run this program as an administrator.”
- Once both of the files have administrative rights, it is time to give folders the full privileges. For that, go to the steam directory C:\Program Files\Steam or browse to the location if you have installed it somewhere else on your PC.
- Right-click the Steam folder and select the Properties from the options. Then, navigate to the Security tab.
- In the security tab, click “Advanced” located at the bottom.
- Here you will find a table, click on the row and select the Edit option. From the list of different options, grant the “Full control” access. Repeat the step for the first four rows and save changes.
- Now, relaunch your Steam. It will have administrative privileges now.
#5 – Power Cycle Computer
If the above methods didn’t work for you, it’s time to power cycle your computer. Power cycle is basically similar to turning off your computer and then turning on again, but better.
There are many reasons why a power cycle method is recommended, such as you might want to recover your computer from an unresponsive state or reinitialize a set of configurations. Moreover, if you want to reset your network configurations, power cycling will make you lose all the configurations.
If you want to power cycle your computer, follow the given steps below:
- Firstly, shut down your computer completely.
- Then, detach all the wires connected to your computer
- Remove the battery of your laptop carefully and hold the power button for 1 minute after detaching the battery
- Now, wait for a few minutes before connecting your battery again. This will make all the capacitors in the laptop discharge and lose all the data stored in RAM.
- After plugging the battery in your laptop, turn it on and check if the problem still persists.
If you are using a PC instead of a laptop, shut down your computer completely and detach all the wired and modules. Take out the power cable and wait for a few minutes. Then plug in everything and check for the error.
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#6 – Try Signing Out And Then Signing In To Your Steam Account
To make sure that the problem isn’t with your account, try signing out of your account and then logging in again. This would set configurations at the place if they weren’t loaded in the first place.
To follow this solution, go through the steps given below:
- First of all, launch the steam client and go to the steam button located on the left of the screen
- Then, select the “Change User” option from the drop-down menu.
- A window will pop up, click “logout” option there to sign you out of your steam account
- Once you have successfully logged out, it’s time to log in again. Enter your credentials and click “sign-in” option
- Now that you have accessed your steam account again, launch your desired game.
#7 – Reinstall CS GO Game And Steam
If the above fixes haven’t worked for you, don’t worry! It is recommended that you try your luck with completely reinstalling CS GO. This will save you time with restarting your computer again and again and trying different configurations that are just going in vain.
To reinstall CS GO, follow the steps given below:
- Launch Steam and go to your steam library, there you’ll find all your installed games listed.
- Right-click the CS GO game and select “Manage” from the drop-down menu and then select “Uninstall” from the next menu.
- The popup window will ask for your confirmation. Select “Delete.”
- Wait until the game is uninstalled completely.
- Now, you’ll need to reinstall the game. You can download it from here.
- After the game installs, check if the VAC was unable to verify the game session error is gone.
Still, if the error continues to pop, you should also try uninstalling the Steam and then install it again. This has worked for many users who faced the same error. If not, then jump to the next solution.
#8 – Temporarily Disable Or Uninstall Third-Party software
Another general fix that has proven to work for other gamers is disabling the third party software temporarily. Sometimes third-party software interferes in launching games.
And, this could be the reason behind the Matchmaking: VAC was unable to verify the game session. To avoid this, make sure you disable or uninstall all the third-party apps available on your PC. You can do that through your control panel.
#9 – Exclude Game Directory From Antivirus Scan
Most of the time, antivirus and games don’t get along. Antivirus flags game as malicious content and blocks it. This results in errors and problems, and one such error is “Vac was unable to verify the game session.”
The default antivirus for windows 10 is the windows defender. It does a pretty great job of keeping the malicious files at bay, but it sometimes blocks the game folders too. Therefore, it is necessary to exclude your game directory from the antivirus scan to avoid the errors.
To do so, follow the steps given below:
- On your computer, open the Windows Defender Security Center by searching it on the windows search bar
- Then, go to the Virus & threat protection option
- Now, locate the “exclusions” tab, by scrolling down, and you’ll find “Add or remove exclusions” option under it
- Now, click the “add an exclusion” button and select the folder or file that you want to exclude from the scan. In your case, browse to the game location and exclude that.
- Follow the on-screen directions afterward.
- Once you have excluded the game folder, launch Steam and start your game.
Hopefully, this exclusion from Windows defender will solve the error for you. Also, if you are using any other antivirus, search over the internet on how to add an exclusion for that for a better idea.
The game errors can be quite frustrating, that too, when it’s your favorite game. But don’t worry, the above-mentioned solutions will work out for you, and you’ll be able to enjoy CS GO in no time again. If these solutions still don’t work for you, seek some help from the steam customer support. Happy gaming!