Read this whole message before doing anything.
Back up all data.
Quit the App Store application if it’s running.
Step 1
Hold down the option key and select
Go ▹ Library
from the Finder menu bar. Delete the following items from the Library folder (some may not exist):
- Caches/com.apple.appstore
- Cookies/com.apple.appstore.plist - corrupt
Leave the Library folder open. Try the App Store again. If it works now, stop here. Close the Library folder.
Step 2
If you still have problems, quit again. Go back to the Finder and move the following items from the open Library folder to the Desktop:
- Cookies/com.apple.appstore.plist
- Preferences/com.apple.appstore.plist
Again, some may not exist. Test. If the App Store now works, delete the files you moved to the Desktop. Otherwise, quit again. Put back the files you moved, overwriting the newer ones that may have been created in their place, and continue.
Step 3
Log out, log in, and try again.