iTunes for Mac (App Store) error 14 update iOS Devices

I have tried to use iTunes for Mac (App Store Version) to update my iPad and iPhone during the last two months.

I have tried it couple of time to update from

- iOS 11.4.1 to 12

- iOS 12 to 12.0.1

- iOS 12.0.1 to 12.1

All of the time, it was failed with error 14.

These were done by

- Always latest version of iTunes

- MacOS High Sierra, Mojeve 10.14, and 10.14.1

- Download .ipsw to store locally on Mac

- Click option+update button

- Connect via genuine cable given by Apple

- Internet work just fine

I couldn't think of anything else that went wrong to make any devices failed to update.

(After each failed attempt, I need to do the same step on Windows to recover my devices).