[Solved-2 Solutions] Error 14 Occurs After iOS 10 Update

Error Description:

Many users have updated their iPhone/iPad/iPod to iOS 11/10 and some of them find themselves stuck with various iOS update and restore errors. Apple has summed up a series of known update errors and their solutions on its support page, but there is no specific solution for iOS 10 update problem.

Note: If we have met with the Error 14 when updating to iOS 11, this guide also can help.

Install Xcode 8 on Mac

If we try to update to iOS 10 with iTunes on Mac, we should make sure that the latest version of Xcode has install on the Mac.
Apple has reminded users that "we must have the latest version of Xcode installed on the Mac before using a Restore image to install iOS or tvOS software on a device".
Therefore, before upgrading the iOS devices to iOS 10, we might want to install Xcode 8 on the Mac from the Apple developer portal or Mac app store so that the error won't occur during the update.

Backup and Clean Restore of iOS 9.3.2

If the Error 14 has occurred before we know the importance of Xcode 8, we can try backing up the iOS device and doing a clean restore of iOS 9.3.2 to fix the error.
Firstly, make a backup of the iOS device. Then do a restore to iOS 9.3.2 with iTunes. Before restoring from the personal backup, use the IPSW file that is downloaded from Apple's Developer to clean restore iOS 10. After iOS 10 beta has installed, we can then restore the backup.