Unable to log in with sandbox test users on device

Question

Trying to do some In App Purchase testing, so I created a sandbox tester on itunesconnect... but when I attempt to log in as that user on my device I get an error:

Answer 1

In my case, just log out your real Apple ID, don't login sandbox tester Apple ID, then run your App, buy product, and system will showing a alert view to let you choose "Use Existing Apple ID" or "Create New Apple ID", of course choose first one, then login your sandbox tester Apple ID, and it's done.