what is unknown error 1671 when updating iphone 5s

Get help with iOS update and restore errors - Apple Support

I've never seen that specific error, but it is in the same range as errors related to inability to contact Apple's activation servers. The possible causes of this problem are:

• Your antivirus or firewall is blocking access to Apple's server address gs.apple.com
• The phone is jailbroken, or has been in the past
• The computer you are using to restore the phone has been used in the past to hack or jailbreak an iOS device

You can try disabling the antivirus and firewall. If the 2nd is a possibility try restoring from DFU mode. If the last one might be a possibility reset the hosts file on your computer to its default. There should be no references to gs.apple.com in it, or to any other apple URL.

Hi Lawrence.

I'm having the same issue: unknown error 1671, but updating iPhone 4S.

I'm using a Mac with updated iTunes. No jailbreak at all!

I'm wandering, I haven't a clue about it.

Look at the other 1600 series errors here: Get help with iOS update and restore errors - Apple Support

Thank you for your quick reply 🙂

I already visited that link.

I keep on trying and I let you know

Just disabled Antivirus for a few mins and it worked. Cheers

I encountered this error when I indicated I did not want to update my OS immediately but went ahead with the option to download the code and update later. The download was running in the background but no status was displayed. Once the download completed, the error cleared and everything proceeded according to plan.