My iPhone 4S is stuck in recovery mode with a broken power button. When I downloaded the latest iOS update via iTunes with my iPhone plugged in to my computer and showing the "Connect to iTunes" screen, it gave me error 21. This has happened every time I have tried to update my iPhone, and I have tried it on multiple computers. What can I do? 😟
iPhone 4S, iOS 8.1.3
This could be a hardware error. If you already tried multiple computers, did you also try another USB cable?
Check for hardware issues
Related errors: 1, 3, 10, 11, 12, 13, 14, 16, 20, 21, 23, 26, 27, 28, 29, 34, 35, 36, 37, 40, 1000, 1002, 1004, 1011, 1012, 1014, 1667, or 1669.
These errors mean that your device or computer may have a hardware issue that's preventing the update or restore from completing.
- Check that your security software and settings aren't preventing your device from communicating with the Apple update server.
- Then try to restore your iOS device two more times while connected with a cable, computer, and network you know are good.
- Confirm that your security software and settings are allowing communication between your device and update servers.
- If you still see the error message when you update or restore, contact Apple support.
copied from Resolve iOS update and restore errors
iPhone 4S keeps giving error 21 when trying to update.
