@User Also one thing to keep in mind is that Apple credentials are tied to bundle identifiers for iOS devices. And the demo app uses a specific library to make it work. If you are testing on an iOS device/simulator and getting the error the bundle ID may be the problem. Also any additional info would help: What OS you are trying it on? Did you use the same library for Apple auth that the demo app does? Did you see an error on the Apple sign in view (that the device renders on iOS or the webpage on Android) or is it a specific API thats throwing it etc etc