It may be the case where Steam downloaded and installed an update.
After every update, it requires that you restart the client properly.
If not, you should try running the verification check again.
If you get an error still, it means that the installed mods on your computer are tampering with the client’s performance.
Like the error states, it found something that it shouldn’t or the mods caused a file to be changed.
What verifying integrity of a game does is check the manifest of your game with that present at the Steam servers.
It is very useful in troubleshooting for errors that we can’t pinpoint.
You can download Reimage Plus by For example, if I am checking drive D, I will write “CHKDSK D:”.
If the manifests don’t match, Steam declares that there is an error and one (or more) files failed to validate and will be reacquired.
In the ideal case, the files should be replaced or removed.
Many users reported that bad sectors in their hard drive were causing the problem.
A bad sector on a computer hard drive is a sector which is unwritable or inaccessible due to permanent damage.