""Operation is not supported on this platform." MacOS

[qrpike]

My Application:

using WebSocketSharp;
using System;

namespace TestProject{
    class Program{
        static void Main(string[] args){
            WebSocket ws = new WebSocket("ws://localhost:9090/ws");
            ws.SslConfiguration.EnabledSslProtocols = System.Security.Authentication.SslProtocols.Tls12;
            ws.OnMessage += (sender, e) => {
                Console.WriteLine("Says:" + e.Data);
            };
            ws.ConnectAsync();
            ws.Send("Auth");
            Console.ReadKey( true );
        }
    }
}

Error:

System.PlatformNotSupportedException: "Operation is not supported on this platform."
  at System.Func`1.BeginInvoke(AsyncCallback callback, Object object)\n   at WebSocketSharp.WebSocket.ConnectAsync()\n   at TestProject.Program.Main(String[] args) in /Users/qrpike/Projects/TestProject/TestProject/Program.cs:15

System Details:

Visual Studio Community 2017 for Mac
Version 7.6.3 (build 1)
Installation UUID: 93217eed-bb8a-4b16-9e34-95aba35b01be
Runtime:
	Mono 5.12.0.301 (2018-02/4fe3280bba1) (64-bit)
	GTK+ 2.24.23 (Raleigh theme)
	Xamarin.Mac 4.4.1.178 (master / eeaeb7e6)

	Package version: 512000301

NuGet
Version: 4.3.1.4445

.NET Core
Runtime: /usr/local/share/dotnet/dotnet
Runtime Versions:
	2.1.2
	2.0.5
SDK: /usr/local/share/dotnet/sdk/2.1.302/Sdks
SDK Versions:
	2.1.302
	2.1.4
MSBuild SDKs: /Library/Frameworks/Mono.framework/Versions/5.12.0/lib/mono/msbuild/15.0/bin/Sdks

Xamarin.Profiler
Version: 1.6.3
Location: /Applications/Xamarin Profiler.app/Contents/MacOS/Xamarin Profiler

Apple Developer Tools
Xcode 9.4.1 (14161)
Build 9F2000

Operating System
Mac OS X 10.13.6
Darwin 17.7.0 Darwin Kernel Version 17.7.0
    Thu Jun 21 22:53:14 PDT 2018
    root:xnu-4570.71.2~1/RELEASE_X86_64 x86_64

[Violetdusk]

.Net Core doesn't support BeginInvoke. The reason is well commented here.

[danielmackay]

This library supports .NET Standard, so this should work on .NET Core right?

I'm having this same issue with basically the same code. How can the code above be modified to work with .NET Core 3.1?

TIA

[otmanel31]

+1 same issue, any hints guys ? i'm on dotnet core 3.1. I test it on windows but it should be deployed on linux then ...

[otmanel31]

without response i switch to a standard websocket client ...