This week was one of those times where I needed to reinstall Leopard on my MacBook Pro. This is something which I do every now and then to make sure the development work i’ve doing hasn’t completely messed up my system. Normally this goes very well but this time iTunes decided to misbehave.

The symptoms

• You try and listen to some songs and you get asked to authorise the computer. You do this but the next song owned by the same account asks you to authorise again.
• When you try and update applications for your iPhone you get an error -5000 on the downloads page
• As with the appstore, you get an error -5000 when podcasts are being downloaded.

The problem

This is such a trivial problem that it took a little while to work out what was going on. What’s happening is iTunes is unable to modify any of it’s files because of the permissions on the iTunes folders.

The solution

If your iTunes library is stored on an external hard drive (mine is), you can tell Finder to ignore permissions on the drive. To do this:

• Click on the drive in Finder
• Choose File -> Get Info (or press Command-I)
• In the bottom right of the information panel that appears, check the padlock is unlocked.
• If it isn’t unlocked, click it and enter your logon password
• Put a tick in the ignore ownership on this volume box

Alternatively, if your iTunes library is in your Music folder:

• Select your Music folder in Finder
• Choose File -> Get Info (or press Command-I)
• In the bottom right of the information panel that appears, check the padlock is unlocked.
• If it isn’t unlocked, click it and enter your logon password
• At the bottom of the information panel click on the gear icon
• Choose Apply to enclosed items – know this can take a while if your library is large

You should now find iTunes is working again.