The Azure AD Connect installation would get to the ADFS Service Account screen (shown below) but would not allow the installation to proceed. After restarting the installation process and walking through the steps several times, the process appeared to be in an infinite loop (see paragraph above). The screen below was the brick wall in the installation process. The account information was auto populated from the existing ADFS farm. The accounts specified throughout the installation wizard are all done in DOMAINUser format. So what’s going on here?
Digging Through the Logs
The Moment of Clarity
So, where is this coming from? In our case, the service account on the Active Directory Federation Services service was configured with the Log On account configured in UPN format. While this is perfectly valid for a service account as far as Windows is concerned, the Azure AD Connect installation has a problem with it.
The solution is easy, just change the service log on information to DOMAINUserName format in the service and the installation will proceed past the ADFS Service Account screen.
Now that we have the Log On information in the service account for ADFS corrected, the installation continues on.