How to Fix iTunes Error 1671 (iPhone Error 1671)
* Wait for a while and try again.
* Update iTunes to the latest version. The current iTunes version available is 12.8, adding support for iOS 12. But you need to know that iTunes won't sync ringtones, apps etc. to iPhone iPad since iTunes 12.7.
* Update your computer. Install macOS High Sierra update for macOS (or macOS Mojove bundled with iTunes 12.9), Or get your Windows updated.
* Restart. Quit iTunes, turn off your computer and iPhone or iPad and turn them again to see if iTunes error code 1671 disappears.
* Directly connect your iPhone iPad to your computer's high-speed USB port instead of an attached keyboard or USB hub if iTunes failed to sync with iPhone, or iTunes doesn't recognize iPhone, as Apple Support suggests.
* Try a different USB cable. Many users are glad to find that this simple action solved iTunes error code 1671.
* Login with your administrative user account, which helps fix iTunes error 1671.
* Check if any software update is available and do the update. It also fixes iTunes error 9006, error 3004, error 3194, or some other iTunes error codes.
* Update, shut up or even uninstall security software that may cause iTunes error 1671 on your computer.
* Try to restore iPhone iPad in DFU mode. iPhone error 1671 should be fixed.
* Connect iPhone or iPad to your computer, open iTunes and try to update or restore again.
* Try a different computer to see if it's the computer that causes error 1671 in iTunes.
* Contact Apple Support to ask help if iPhone error 1671 still exists in iTunes when restoring, updating iPhone or iPad.
Also See: How to Fix iTunes Error 9, Error 14, Error 1671 , Error 54, Error 39