I have configured the Azure front door to work with the app service. Then I added the AAD B2C login by using the custom policy. The AAD B2C doesn't work with Azure front door because the return uri still points to the app service as the following:
https://<tenant-name>.b2clogin.com/<tenant-name>.onmicrosoft.com/b2c_1a_signin_only/oauth2/v2.0/authorize?client_id=c1f576c3-d0da-4752-b925-78fc186a29e5&;redirect_uri=https%3A%2F%2F<app-name>.azurewebsites.net%2FManagement%2F&response_type=......
instead of the azure front door address <Front Door host>.azurefd.net or our custom domain which directs to <Front Door Host>.azurefd.net.
I have added the <Front Door host>.azurefd.net and custom domain as the redirect URIs under the authentication for the app registration on AAD B2C.
I have also tried with blanking out the Backend host header in Backend pools. The return uri still points to the app service which is blocked out form direct access.
How to make AAD B2C to return to Azure front door instead of app service?