I have a family member that did something a bit carelessly (but with good intentions) and I'm trying to help fix it.

They upgraded their iPhone 4 to iOS 5, but they did it from a different computer/iTunes than the one their iPhone was associated and synced with. This wiped out everything on the iPhone, of course.

Now I'm trying to help them restore data, apps, music, etc. There was a device backup in iTunes on the old laptop so I copied the contents of the MobileSync folder between the two systems. On the new laptop, I restored from backup via iTunes. Then, I proceeded to download all previous purchases in iTunes (apps, music), and then tried to sync:

  • First I synced apps only. No problemo.
  • Then I added music to the sync settings. Houston, we have a problem.

When I try to sync music it says that the iPhone is associated with another iTunes library and the phone will be erased. Ugh. If I only try to sync apps, there isn't an issue. But of course, they want their music copied back to the iPhone. :)

In short, how do I accomplish all of the following:

  • Restore important data from the iTunes device backup copied from the old laptop
  • Ability to sync all purchased/future purchases of music
  • Ability to sync all purchased/future purchases of apps

Thanks in advance!

  • Edited question.
    – user14395
    Commented Dec 23, 2011 at 19:15

3 Answers 3


Note: This is all done on a Mac. Just look up the PC equivalent of the following steps if required.

How to recover past information:

Option 1 - Restore iPhone 4 directly from old computer:

  • Connect iPhone 4 to old computer, open iTunes, put the iPhone in DFU mode, (while holding alt/option key) select Restore after iTunes has detected the iPhone 4 in recovery mode, and select the most recent backup of that iPhone 4.

Option 2 - Copy iPhone 4 backup from old computer, and place on new computer to recover:

  • On the old computer, go to ~/Library/Application Support/MobileSync/Backup, and copy the most recent backup of the iPhone 4 and transfer it to the new computer.

  • Connect iPhone 4 to old computer, open iTunes, put the iPhone in DFU mode, (while holding alt/option key) select Restore after iTunes has detected the iPhone 4 in recovery mode, and select the most recent backup of that iPhone 4.

How to create the ability to sync all purchased/future purchases of music and apps:

  • Open iTunes.

  • Sign out any pre-existing AppleID/iTunes Account once iTunes loads.

  • Sign into desired account of individual (your relative's I'm assuming).

  • In iTunes, select Store -> Authorize This Computer...

  • Rejoice!

  • Have your relative use iCloud for backup to make life easier in the future.

Let me know if you have any more questions, or need any futher explanation. Enjoy!


You need to roll-back and roll-forward.

  1. Attach the iPhone to the old laptop.
  2. Open iTunes.
  3. Click the restore button to restore it to an old backup before the upgrade (it will get all the music back).
  4. Upgrade the iPhone while attached to the new computer.

That should get you there. In your question you didn't say which computer you wanted to sync with when you were done. Switching computers is a complication.

  • Yeah...sorry for being unclear. I think the reason they did it this way is that the old computer is painfully slow. I remoted in to help and I waited 5 minutes just for a Windows Explorer window to open :(.
    – AJ.
    Commented Dec 22, 2011 at 17:45
  • Apple does not allow you to move songs off of an iPod/iPhone. There is a program called MediaMonkey that does support it to a degree. Otherwise move all the songs from the old computer to the new, and then sync it with the new computer. Commented Dec 24, 2011 at 17:25

do you know if you still have the pre-iOS 5 backup on the original computer? if so, try -

  1. connect the iphone to the original computer that it used to sync to before it was updated
  2. restore the iphone backup (pre iOS 5) to the iphone via itunes
  3. update the iphone to iOS 5 using the original computer

if you're stuck with the new computer, try copying the old itunes library to the new computer and then sync.

  • can you please be more specific when you say "the old itunes library"? An entire folder (and which one)? Specific files and/or sub-folders within an iTunes-managed folder?
    – AJ.
    Commented Dec 19, 2011 at 22:19
  • this would be the itunes library located on the old computer in it's default location of - 'your hd name'/'your user name'/Music/iTunes/ Copy the entire iTunes folder to the new computer, replacing /Music/iTunes/ (keep in mind this will overwrite the iTunes library on the new computer)
    – roybatty
    Commented Dec 22, 2011 at 15:17
  • 1
    BTW, if you don't want to overwrite on the new computer, you can copy the old library anywhere on the new computer and hold option when starting iTunes to select different libraries.
    – roybatty
    Commented Dec 22, 2011 at 15:24

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .