iTunes update Failure error 103

Try each of the following steps.

Step 1

If you're trying to install more than one update, do the updates one at a time.

Step 2

Triple-click the line below to select it:

/Library/Updates

Right-click or control-click the highlighted line and select

Services ▹ Open

from the contextual menu. A folder should open. Move the contents to the Trash. You may be prompted for your administrator password.

Thanks Linc for this information. I had the same problem and your solution allowed me to update.🙂