For me this happened because the service shut itself down each time it was started as it was recognizing another service on the network. It stayed online long enough to start the registration but then shut down by the time you reach this step. I had to make sure the other service was stopped before starting the new one.

One strange thing that happens during a migration is that it asks you what the name of the repository is, not sure why since it should know it's own name, but you have to manually enter it without any mistakes for the new server to work. To get the name you have to start the old service, so having the old service running while registring is super common.