we could not complete your iTunes store request. An unknown error occurred (4200)

When I sync the iphone 4s after updating the apps on the download section, I get the error code : we could not complete your iTunes store request. An unknown error occurred (4200).

iTunes updates the phone as far as I know, but clearly there is some sort of error or fault. I have looked for code elsewhere and googled it too without success.

Anyone else come across the same problem?

Thanks