Ok if you’re trying to run it with IIS Express in the issue is due to multiple URL bindings, from: Invalid application pool name
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.
Rider/VS Code doesn’t have this issue as it just runs the .NET Core App normally.
ASP.NET Framework Templates project
If you did want to create a .NET Core App you can instead use the ServiceStack ASP.NET Templates with Bootstrap project from ServiceStackVS:
Troubleshooting
If you still can’t run the project after changing the port, close the solution and delete the .vs/ folder than try re-opening and rerunning the project again.