iPhone will not sync - says "an unknown error occurred (-54)".

Hello ClayinNJ,

Thanks for reaching out to Apple Support Communities.

Let's review the steps here. These cover a number of possible solutions for errors like this: If you see an error when you update or restore your iPhone, iPad, or iPod - Apple Support

1) Update your Mac or PC

Update your Mac. Or if you have a PC, get updates from Microsoft. If you're using iTunes, make sure that you have the latest version of iTunes.

2) Plug your device directly into your computer

Plug your iPhone, iPad, or iPod directly into your computer's USB port (not into an attached keyboard or USB hub). Make sure that the cable is in good condition.

Make sure that your device is unlocked. If prompted, trust your device.

If you still see an error alert, try a different Apple USB cable or switch to a different USB port on your computer.

3) Restart your computer and your device

Turn off your computer, then turn it on again. Next, restart your device.

Learn how to restart your iPhone, restart your iPad, or restart your iPod touch.

4) Check your computer’s security software

You might need to update, change, or uninstall software that could be interfering with your computer's connection with iTunes.

5) Use a different computer

Update or restore your device on another computer that uses a different network.

If the issue persists, Contact Apple for support and service

Cheers.