We are not able to register the new HDP version in Ambari 2.7.4 without GPL with the LOCAL Repository.
This issue is related to local repository validation with Ambari. We can skip the validation check and register the version. Or else we can enable the GPL and successfully register the version without "skip the validation check".
If we have disabled the GPL then we will get this issue. This issue is not occurring with the public repository. I have tested the same in my cluster with the public repository.
I have attached a ScreenShots.