Updating error there was an error performing the update mac
But remember that restoring i OS software also removes all your data and contents from your device like songs, videos, contacts, calendar info and photos.
That's why it is highly recommended to back up your device first, using i Tunes and transfer/sync any additional contents to your computer.
Update to i Tunes 12.5.4 or later to fix error 1671.
If you see error 1015 or a message that says, "The required resource can't be found," your device might have unauthorized i OS modifications ("jailbreaking").
These error codes have something to do with a security software that is preventing your computer from communicating with either your i OS device or the Apple update server.