Several iOS 10 beta users have been seeing the infamous error 14 message after trying to install Apple's newest update on their devices. It is confirmed that the problem occurs when users try to update the software while also restoring data from the backup.
Unlike iOS 8 or iOS 9, restoring data from backup is no longer possible in iOS 10 due to some source code changes implemented by Apple with the new update. However, affected users could try restoring data from backup once the installation is done.
Meanwhile, several users have reported on MacRumors thread that changing cables or using the DFU mode does not help in fixing the problem.
Here is how you can fix this problem:
- Perform a full backup of your important data and settings on the device via iTunes. Now do a clean restore of iOS 9.3.2 without selecting your personal backup files.
- Then do a clean restore of iOS 10 with the IPSW file you downloaded. You can restore the backup files after the iOS 10 installation is done.
- Do remember that you need Xcode 8 installed on your Mac before using a restore image (IPSW file) to install iOS or tvOS beta software on your device. Use the option key to do a clean restore via Xcode 8.
- If the issue persists verify your USB device is working or trying using another device.
- Alternatively, try installing the iOS 10 beta directly on the device with over-the-air (OTA) Configuration Profile and that could fix the issue.