My new iPhone 6s Plus is not allowing me to use cloud for set up because my old phone, iPhone 5c is running on a different IOS, 10.3. The new phone was never upgraded from 9.3.
Is there a way around this issue. I want my new phone on IOS 11.
Assuming your "new" iPhone is truly set up as brand new software-wise (as if it just came out of the box for the first time), do Settings > General > Software Update on that iPhone.
If it is not currently set up as brand new, you should do this first:
Settings > General > Reset > Erase All Content and Settings
... and then do the software update as above.
Then you will be invited to restore that iCloud backup.
Assuming your "new" iPhone is truly set up as brand new software-wise (as if it just came out of the box for the first time), do Settings > General > Software Update on that iPhone.
If it is not currently set up as brand new, you should do this first:
Settings > General > Reset > Erase All Content and Settings
... and then do the software update as above.
Then you will be invited to restore that iCloud backup.
Upgrade the new iPhone
Set up new iphone 6splus that is still on IOS 9.3
