Q: My PC hard drive is getting a bit full, and I was browsing various folders to see what could be deleted to free up a bit of space. In my iTunes folder I found a sub-folder called “Previous iTunes Libraries”. The files date from 2006 through to March 2011. Sizes vary from 2Gb to 10Gb, and have a total size of 56Gb. What exactly are these files, and can they be deleted to free up some space? Or does iTunes need them for something, and will it corrupt anything if I delete them?
A: Often when upgrading iTunes, particularly to a major new version (e.g. iTunes 9 to iTunes 10), the iTunes library database is changed to support new features. As a result, it is impossible to downgrade to a prior version of iTunes using the same database—the older version cannot read the new format.
The “Previous iTunes Libraries” folder simply contains a backup of iTunes libraries from these prior iTunes upgrades that can be used to restore your iTunes library in the event that you have a problem with the newer version. These files are not used by the current version of iTunes in any way, and are simply backups. You can remove them at your leisure.