How do I fix error 14 on iTunes?

According to Apple, this particular error is most commonly caused by issues with your USB cable.

iTunes error 14 is often caused by a faulty firmware update file. So check your device’s USB connection, the USB (Lightning) cable, and your computer’s or power strip’s USB port for any obstructions.

Here's what to check. Try again after each step:

1. Use the USB cable that came with your device. If you don't have it, try a different Apple USB cable.
2. Switch to a different USB port on your computer. Don't plug into your keyboard.
3. Switch to a USB port on a different computer.
4. If you still see the error, check for other USB issues, check your third-party security software, then check your hardware.