Azure AD Connect swing migration when using ADFS

[RNalivaika]

Hi, one of my customers runs an old version of Azure AD Connect with ADFS. I were planing to build a new AADC server and set it to staging mode to do a "swing" migration .

But when configuring new AADC, I am presented with a list of UPN suffixes used in the domain and I have to choose which one to federate with Azure AD. I was not expecting this, as all the UPN suffixes in the list are already federated by using the old AADC server. Is it safe to just let the wizard federate again, or will this break federation activated on the old server? Or is the process for swing migration when using ADFS different than when not using ADFS? Switching away from ADFS to other authentication is not relevant yet. Thanks, Ruslan

[#2]

Are you importing the exported configuration from the production Azure AD Connect?

[#3]

Yes

[#4]

@RNalivaika Hi, what was your solution? I am facing something similar at the moment. but in my case the dropdown for the federated domains is empty. 

[#5]

@Michael85 Hi, I just chose a random domain from the list and continued onward with the wizard. I selected 'staged mode' to begin with, it did not do any harm to the config, the old azure ad connect server was still working fine. I have since finished the swing migration and using supported version fine now. It's difficult for me to say what might be your issue, but maybe the wizard cannot contact the adfs farm to pick up adfs config with federated domain? that would be my first guess. 

-Ruslan