Somehow I’ve managed to break my Mac OS software updates / iTunes. I cannot remember doing anything special than updating software when I got a notification from my operating system. I think there were 5 updates and I just activated updating them all. After the third package had been updated an error occurred.
In such case I suspect some network problems and try again. But it didn’t work. So my suspicion readjusted itself towards caching. Software often includes retry timeouts to avoid wasting too much resources in the unusual case. So I waited for a day and retried then. Nothing changed, still broken! Well, I thought if the system is updating its software catalog it could fix the entry if it is bogus. This story could go on for some more time. As a software developer I’m experienced with all sorts of problems that can occur in those situations. But even waiting for a whole week didn’t help. The packages didn’t want to update.
A short research showed it is possible that the software registry of installed packages can become corrupted. One way to fix this is to reset software registry.
Open a terminal and execute the following line
defaults write com.apple.appstore ShowDebugMenu -bool true
Open software updates application and you should see an additional menu entry Debug on the right. In the Debug menu you’ll find an entry called Reset application. Restarting the sofwtare updates application should reload its data and the problem should be fixed.
I’ve found this information on this thread