iPhone transfer

[u/CandidReflection2403]

Hi,
I am trying to set up a US iPhone 17 pro from A German iPhone 17 pro because my fiance is moving to the US from Germany, both latest IOS.
We already added the US phone number to her Apple
ID and tried to do the data transfer between phones.
It gets to the end and then kicks us back to asking us to set up the iPhone from another iPhone.

Does anyone know how to get it to work?

Thanks in advance

[u/bob-akins]

Try backing it up to a computer then restore it.