Here's a sledgehammer approach:
Quit the Mac App Store App and in terminal
open $TMPDIR../C/com.apple.appstore/
open ~/Library/Caches/com.apple.appstore/
open ~/Library/Caches/com.apple.appstoreagent/
Delete the contents of all the folders.
Open the
Activity Monitor and set its view to
All Processes. Type in
store to search for App Store related processes, and force-quit all of these daemon processes:
- storeuid
- Appstoreagent
- storedownloadd - Handles downloads of apps found in the App Store.
- storeinstalld - Covers app installation and their updates.
- storeassetd - Handles all the resources and language files of the App Store.
- storeaccountd - In charge of authentication, and acts as a bridge with your Apple ID account.
In terminal:
open ~/Library/Preferences
Here, delete the following files:
- com.apple.appstored.plist
- com.apple.storeagent.plist
- com.apple.preferences.softwareupdate.plist
open ~/Library/Cookies
Delete this file:
- com.apple.appstore.binarycookies
Choose
Apple Menu > Restart.
Open App Store, log back in. Your problems should be gone.