Changing the AAD Connect 'User Principal Name' attribute from mail to userPrincipalName?

[Daniel Niccoli]

Hi,

I'm planning to change the User Principal Name attribute from mail to userPrincipalName.

(The top right sync option in the image below.)

I'm wondering whether this has any effect for my existing users?

Will the UserPrincipalName attribute in Azure AD for existing users be stay unchanged, or will it be updated with the on-premises UserPrincipalName?

In either case, I do not expect any disruption at user sign-on, as we use ADFS, so the sign-on attribute is independently defined in in the claim rules. Am I correct with this conclusion?

[#2]

@Daniel Niccoli it would affect those users who do not have a match on UserPrincipalName and Mail. Thus updating the UserPrincipalName those users in Azure Active Directory. As long as you do not alter the source anchor, you should be fine.

Which attribute to you use in the ADFS claim?