Fix: iTunes was unable to load dataclass information error

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I recently installed XCode 4 off the Mac App Store. Once that was done, i found that iTunes started throwing me the “iTunes was unable to load dataclass information from Sync Services” error every time I try to plug in the iPad and iPhone to sync via iTunes.

Darn! Looks like the Xcode 4 install screwed up iTunes in some way.

Searching the error on the Internet pointed me to a fix posted in Apple’s support site. It’s basically a guide to remove and reinstall the Apple Mobile Device Service on Mac OS X. Well, it does sound like that’s my problem. The steps to do so are as the following:-

  1. Disconnect your iPhone, iPad, or iPod from the Mac.
  2. In the Finder, locate iTunes in the Applications folder and drag it to the Trash.
  3. Move the iTunes icon to the Trash.
  4. Choose Go > Go to Folder.
  5. Enter /System/Library/Extensions and click Go.
  6. Locate the file AppleMobileDevice.kext and drag it to the Trash.
  7. Choose Go > Go to Folder.
  8. Enter /Library/Receipts/ and click Go.
  9. Locate the file AppleMobileDeviceSupport.pkg and drag it to the Trash. If prompted, authenticate with the administrator password.
    Note: This file may not be present in Mac OS X v10.6 and later; skip to the next step if this is the case.
  10. Restart the computer.
  11. Choose Finder > Empty Trash and restart the computer.
  12. Download and install the current version of iTunes.
  13. Connect your device to the Mac again and open iTunes

Seems simple to follow, but if you noticed the steps, it does involved removing iTunes and re-installing it. And if you ever had to rebuild iTunes from scratch, such as when switching machines, or reinstalling your OS (especially when I was still on Windows), losing all your data on iTunes is a real pain to recover from.

So, yes, I’m sure you’ll be hesitating to follow these steps too. But, not being able to sync properly on iTunes is worse. Therefore, I did exactly as per the above EXCEPT for step 11, which is to empty Trash. I was afraid to lose anything, so I left the Trash alone, hoping I can recover iTunes just in case things screwed up.

And guess what, nothing was gone. 🙂 The guide from Apple works like a charm and I was able to sync my phone and iPad back again with everything left intact in iTunes. PHEW!

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14 Responses

  1. yeppp :) says:

    i had the same problem, but luckily this solution saved my day 🙂
    anyway itunes stores the data in Library, not in Application… this is why we got back everything as it was before 🙂

  2. Patrice says:

    Worked perfectly. Thank you!

  3. acs says:

    Thank you! This fixed the problem perfectly!

  4. pjb3 says:

    Just had to do this to fix iTunes after installing XCode 4 via App Store. Instructions worked.

  5. I just had this problem, too, when I tried to backup my iPhone. I found this page, and when I saw the connection to installing XCode 4, I knew I was on the right track. Anyway, the fix worked for me too. Very much appreciated!

  6. Tldelaney says:

    Awesome post. Thanks a lot!!!

  7. Works pretty well now. Thank you for this post!

  8. John L says:

    had the same prob. read these comments and tried the following short-cut: just moved Xcode to the trash and was then able to sync iTunes to iPhone again

  9. Anonymous says:

     had exact same problem.. just downloaded itunes from apple website and installed right over top.. did not thing else.. got rid of problem..

  10. Remarksman says:

    Same problem — so far I pretty much hate xCode 4!

  11. Philippe says:

    Thanks, you saved my life!

  12. Thank you that worked my syncing is fine again.

  13. Alan Duncan says:

    This same error occurs with iTunes 11.0.4 after installation of Xcode 5 DP3; but the fix does not work.

  14. Ken Ng says:

    Hmm. Let me look into this and see.

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