NancyFx not working on .Net Core 3

[rock85mx]

• I just to migrate mi proyect from net core 2.2 to 3.0, and nancy dosnt work.

• Nancy version: 2.0

• Microsoft.Owin: 3.0

• Startup.cs

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
app.UseOwin(b => b.UseNancy());
}

using Nancy;

namespace WebApplicationCore
{
public class Index : NancyModule
{
public Index()
{
Get("", args => Root());
}

    public Response Root()
    {
        return Response.AsText("Server up");
    }
}

}

[klym1]

I've had exactly the same problem! It appeared that starting from .Net Core 3 it is forbidden to use Kestrel's synchronous API by default (the sync API is apparently used by Nancy as a middleware). So the fast workaround for this issue is to allow synchronous API in Kestrel settings:

var host = new WebHostBuilder()
      .UseKestrel(o =>
      {
      o.AllowSynchronousIO = true;
      })

But, of course, it would be much better if somebody made a PR and let Nancy Owin wrapper use async api.

[RamkiPannerselvam]

Even I was facing the same issue when I use the latest version of .NET CORE 3.1 and the nancy version is 3.1.0. After a lot of research, I have found this answer. The above solution is working fine.

The alternative solution is, you can downgrade the nancy version to 2.2.0 if you want.

[moh-hassan]

a wiki page Hosting Nancy on ASP .NET Core 3.1 (using Kestrel) describe in detail how to use NancyFx with ASP.NET CORE 3.1