[SOLVED] Sustainsys /Saml2/Acs url not found in ASP.NET Core 3.1

Sustainsys /Saml2/Acs url not found in ASP.NET Core 3.1

I am trying to use Saml2 from Sustainsys in an ASP.NET Core 3.1 web app as service provider. I am using the nuget package Sustainsys.Saml2.AspNetCore2. It works fine with a local test IDP in docker container kristophjunge/test-saml-idp, but when I deploy the site to Azure then the url /Saml2/Acs for assertions cannot be found.

This happens after the user is sent to the Azure B2C IDP for login, the user logins successfully and then the Azure B2C calls the assertions consumer service which is /Saml2/Acs but it cannot be accessed by Azure B2C. The metadata url /Saml2, however, is accessible.

Accoridng to the Sustainsys docs:

The ASP.NET Core 2 Handler is compatbile with the ASP.NET Core 2.X and 3.X authentication model.

What could be missing or wrong? Can someone confirm that the nuget package can be used in ASP.NET Core 3.x?

Thanks

Solution

If the metadata URL /Saml2 responds, the handler is running.

Are you sure that /Saml2/Acs is not accessible? It's not just that there is a configuration error causing the response validation to fail? Do you see anything in the logs?