I am facing the below issue, when an Azure Government cloud user is trying to access an web app hosted in Azure commercial cloud. I confirm that the reply url is present in the app registration
Sorry, but we’re having trouble signing you in.
AADSTS50011: The reply URL specified in the request does not match the reply URLs configured for the application: '7c528ed8-8f39-4efe-8ac2-c5a6d108def7'.
This error occurs when the redirect_uri in the authentication request doesn't match with the redirect uri registered in the App registration. When you access the web application, you get redirected to https://login.microsoftonline.com/... url.
Below is an example of authentication request, where the redirect_uri is https://jwt.ms, which must match with the redirect uri registered under app registration. https://login.microsoftonline.com/your_tenant.onmicrosoft.com/oauth2/v2.0/authorize?client_id=574c674d-xxxx-xxxx-xxxx-xxxxxxxxxxxx&response_type=code&redirect_uri=https://jwt.ms&state=1234&response_mode=fragment&scope=https://graph.microsoft.com/.default
If you still face any issues, please share the Correlation ID, Request ID and Timestamp that you are getting along with the error and I will try to track the information in our backend database for you.