About an hour ago i got the same error while updating my game so I’ve searched for the cause of the problem. Luckly, SEGA was propt to release a solution for this on their forum. I will explain it here as well.
They say that it may be the case that the game files have become corrupted and you should try verifying the game cache as detailed below:
– Open Steam application
– Access your Games Library (top menu: “Games” -> “View Games Library”)
– Right-click on Football Manager 2013 on the left and select “Properties”
– Click on the “Local Files” tab
– Select “Verifiy integrity of game cache”
– Wait until this process is finished – This should certify that all files have been downloaded successfully
– If some files need to be reacquired, please repeat the process once more
– When all files have been successfully validated, click on “Play” to start Football Manager 2013
– Wait a moment for some files to download; the game will start automatically afterwards
If after this the game doesn’t start, just restart Steam. Then it should work. Aaand… the worst case scenario, reinstall the game. Then clear the cache and then it should work. But i don’t think that such drastic measures are required.