NancyFx not working on .Net Core 3 about nancy HOT 3 OPEN

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.

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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.

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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

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