Two factor authentication not working on iPhone 4, can't sync with iCloud
The two factor authentication is not working on my iPhone 4, so I can't sync it with iCloud and backup my hundreds of contacts. What can I do?
iPhone 4
Question marked as
See the following from Two-factor authentication for Apple ID - Apple Support
If you use two-factor authentication with devices running older OS versions—like an Apple TV (2nd or 3rd generation)—you might be asked to add your six-digit verification code to the end of your password when signing in. Get your verification code from a trusted device running iOS 9 and later or OS X El Capitan and later, or have it sent to your trusted phone number. Then type your password followed by the six-digit verification code directly into the password field.