What is Error (4000)

What is Unknown Error 4000 that didn't allow me to do latest update 11.1.2 on my new iPhone 7.

How frustrating. I have no idea why this would occur. Was doing it from iTunes as when I opened iTunes to do an import. It asked if I wanted to backup my phone and download the update and I said yes. Now after over 30 minutes I get this stupid error message so now I have to start over. Not happy. Loosing faith in apple.