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I keep getting 'Unknown Error occurred 21' while trying to restore

38013 Views 8 Replies Latest reply: Jun 24, 2013 7:50 AM by charliethebear RSS
Torben.Busk Level 1 Level 1 (0 points)
Currently Being Moderated
Apr 22, 2012 12:54 PM

It started with the apple logo just flashing on and off. So I went to reset my daughters iPhone by pressing the on/off button and the menu button simultaneously until the iTunes logo and the USB cable was shown on the screen. At that point, iTunes wrote;


'iTunes has detected an iPhone in recovery mode. You must restore this iPhone before it can be used with iTunes.


I clicked 'OK' and then 'Restore'. ITunes then went on by 'extracting software...' for a minute or two and then 'Preparing iPhone for restore...'  The apple logo was then shown on the iPhone and a message box i iTunes;


'The iPhone 'iPhone' could not be restored. An unknown error occurred (21)'

The message box leads to 'More Information' that says that the error 21 ' typically occur when security software interferes with the restore and update process'




That's it. I have tried everything. (I think);


Checking for iTunes updates

Checking for OS (Win7) updates

Restarting the computer

Changed the USB cable

Changed the computer

Ensuring that I have administrator privileges and that iTunes has it as well.

Disabling the antivirus

Disabling the firewall


If you have any advice, please let me know.



Torben Busk

iPhone 4, Windows 7


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