In file GrpServer.cs, the StopAsync method:

        public Task StopAsync(CancellationToken cancellationToken)
        {
            return _host?.StartAsync() ?? Task.CompletedTask;
        }

Should be

        _host?.StopAsync(cancellationToken) ?? Task.CompletedTask;

instead.

Also, in StartAsync the cancellationToken is not passed:

    _host.StartAsync(cancellationToken);

I created a new WPF (.net core 3) project, and put the codes in MainWindow.xaml.cs. I'm getting an error:
host = new HostBuilder()
.ConfigureServices(services =>
{
services.AddStandaloneGrpcServer(o => //this line generated the error
{
// Change the port
o.ListenLocalhost(5007);
});
})
.Build();

Error is: CS1061 'IServiceCollection' does not contain a definition for 'AddStandaloneGrpcServer' and no accessible extension method 'AddStandaloneGrpcServer' accepting a first argument of type 'IServiceCollection' could be found (are you missing a using directive or an assembly reference?)

I've added the nuget package grpc.aspnetcore.server version=2.25.0
please advice on what I did wrong.. thank you.