The issue is from VS.NET trying to run the Web App under the default .NET Core 2.1 multiple bindings, i.e. http://localhost:5000/;https://localhost:5001/, but will work if you change it to an unused port, e.g:
It will also work on http://localhost:5000/ if you run VS .NET as Administrator where I’m assuming has permissions to override any previous registration on that port.
From what I can tell VS .NET and IIS Express doesn’t support .NET Core 2.1’s default use of multiple http/https bindings.