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How to fix an unknown error occurred (4000) in iTunes (Nothing else worked)

What is iTunes error 4000 caused by? How to fix it?

This error appears when you tried to update your iOS device via iTunes, but the update failed to complete.

The most common causes of iPod touch, iPad, or iPhone could not be updated. An unknown error occurred (4000) are:

  • Corrupt software update files, possibly due to the Internet connection;
  • Incomplete installation of iTunes (due to malicious software, interferences from other programs);
  • Corrupt registry files;
  • Malicious infection that corrupted system files;
  • Hardware defect (bad USB ports, lightning cable).

Before proceeding further, make sure to check your device if it has already been updated to the latest version, because sometimes iTunes might fail to notify you about that (due to the reasons mentioned above). Also, ensure to stay by your PC all the time, while the updating process is taking place, as you might be asked to provide your passcode or fingerprint.

Select specifications which apply:

Click on this if you use an iPhone.

Click on this if you use an iPad.

Click on this if you use an iPod touch.

Click on this if you tried all the other solutions, but none of them worked.

  1. Take your iPhone to a repair shop

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