Unknown error in App Store Cannot download updates.

Saw that issue has be raised before but could not find a solution. Trying to update some apps, get this message: "There was an error in the App Store. Please try again later. (4)" Checked that my Apple ID, password, etc. are correct. Using Mountain Lion 10.8.5, on iMac, version of App store is q.2.2. Help needed. Stuck. Thanks