topic Re: How to properly register COM components from .NET48 to .NET8.0 in .NET Forum

How to properly register COM components from .NET48 to .NET8.0

18636681122 — Mon, 18 Aug 2025 03:16:07 GMT

This is my .NET4.8 reg method:

cd <cadPath> C:\Windows\Microsoft.NET\Framework64\v4.0.30319\regasm <MyNET48Program>.dll /tlb

But in NET8.0 tlb can't be created, so I try a simple com demo:

using System.Runtime.InteropServices; namespace MyCom; [ComVisible(true)] [Guid("4FB4A212-AE3B-4D3B-9262-FC2DE2D11098")] [InterfaceType(ComInterfaceType.InterfaceIsDual)] public interface IServer { double Add(double a, double b); } [ComVisible(true)] [ClassInterface(ClassInterfaceType.None)] [ProgId("MyComApp.Server")] [Guid("648D8C69-C5B2-45AF-9F22-E6AD2E869B20")] public class Server : IServer { public double Add(double a, double b) => a + b; }

.csproj:

then I get one `MyCom.comhost.dll` and move all files(include MyCom.dll) to acad.exe path(D:\Software\AutoCAD\AutoCAD 2026)

In this path reg:

regsvr32 MyCom.comhost.dll

MessageBox say reg success!

In VB6.0 I write a test：

Private Sub Form_Load() Dim cad As Variant Set cad = CreateObject("AutoCAD.Application.25") Dim o As Variant Set o = cad.GetInterfaceObject("MyComApp.Server") Dim res As Double res = o.Add(1.2, 3.4) End Sub

Error in "cad.GetInterfaceObject("MyComApp.Server"), com components can't be find, C# has same problems.So how can i do?

Re: How to properly register COM components from .NET48 to .NET8.0

norman.yuan — Mon, 18 Aug 2025 15:18:36 GMT

Have you read this post in Autodesk ADN's "AutoCAD DevBlog":

https://adndevblog.typepad.com/autocad/2024/12/bridging-the-net-core-and-autocad-2025-exposing-and-using-com-server-components-with-getinterfaceobject.html

Re: How to properly register COM components from .NET48 to .NET8.0

18636681122 — Tue, 19 Aug 2025 01:51:41 GMT

Hello, thank you for your attention to this issue.

I read this blog post and tried it, but his situation was slightly different from mine; I needed to call the COM component in the exe programme, which is the way of plugins.I registered as the blog post did, using VB6 and C# to find my components and they all failed：

Dim cad As Variant Set cad = CreateObject("AutoCAD.Application.25") Dim o As Variant Set o = cad.GetInterfaceObject("AutoCADComDemo.Server")

dynamic acadApp = null; try { Type t = Type.GetTypeFromProgID("AutoCAD.Application.25"); acadApp = Activator.CreateInstance(t); if (acadApp != null) { string progId = "MyComApp.Server"; dynamic server = acadApp.GetInterfaceObject(progId); var ret = server.Add(3.1, 4.2); Console.WriteLine(ret); } } catch (Exception ex) { }

I don't know what's wrong, can you help me take a look?

Re: How to properly register COM components from .NET48 to .NET8.0

18636681122 — Tue, 19 Aug 2025 01:55:34 GMT

C# code should be：

string progId = "AutoCADComDemo.Server"; dynamic server = acadApp.GetInterfaceObject(progId); var ret = server.ComputePi(); Console.WriteLine(ret);

But it doesn't really matter, the general direction is like this.