Fixes to try
The following are a few methods that have helped many CS: GO players. You don’t have to try them all; just work your way down the list until you find the one that works for you.
Method 1: Restart your Steam client
You may get this error because there are some corruption issues with your Steam client. To fix those issues, you should restart your client:
1) On your Steam client, click Steam in the upper left corner, then click Exit.
2) Open your Steam client again.
3) Click Steam in the upper left corner, then click Go Offline.
4) Click RESTART IN OFFLINE MODE.
5) Click Steam, then click Go Online.
6) Click RESTART AND GO ONLINE.
7) Launch your game
If this method works for you, you won’t see the error again. But if not, there are three more fixes to try…
Method 2: Verify your game files
The error may occur on your CS: GO game because there are integrity issues with your game files. You should check your game files with your Steam client to see if that’s the case for you:
1) On your Steam client, click LIBRARY.
2) Right click your game (Counter-Strike: Global Offensive) and click Properties.
3) Click the LOCAL FILES tab, then click VERIFY INTEGRITY OF GAME FILES.
4) Wait until the process completes, then click CLOSE.
5) Launch your game. Then check to see if the error’s gone.