iTunes could not back up the iphone because it has not been set up yet
My iphone 4s stuck on the 'Slide to Upgrade' screen after upgraded to IOS 9. I made no iTunes backup before, so I follow the fix from Apple --
STEP3. If you made an iTunes backup of your device before updating to iOS 9, STrestore your device from that backup. If not, you need to make a backup of your device in iTunes, then restore from that backup.
But iTunes told me "iTunes could not back up the iphone because it has not been set up yet".....How can I make a backup now?