Unhandled exception when you pass non-public class object to COM DLL in Visual Basic .NET (317273)

SYMPTOMS

When you pass a non-public Visual Basic .NET class object to a Visual Basic Component Object Model (COM) dynamic-link library (DLL), you may receive the following error message:

An unhandled exception of type 'System.InvalidCastException' occurred in ConsoleApplication1.exe

Additional information: No such interface supported

Note In this error message, ConsoleApplication1.exe is the name of your application .exe file.

MORE INFORMATION

Steps to Reproduce Behavior

Create Legacy Component in Visual Basic 6.0

Open Microsoft Visual Basic 6.0.
Create a new Visual Basic 6.0 ActiveX DLL project. Class1 is created by default.

Add the following code in the general declarations section of Class1:

Public Sub LegacySub(ByRef arg As Object)
    arg.f
End Sub

Save and compile the project.

Create Visual Basic .NET Application That Uses the Legacy Component

Start Visual Studio .NET.
Create a new Visual Basic .NET console application. Module1 is created by default.
To add a reference to the legacy COM DLL that you created in the previous steps, follow these steps:
1. On the Project menu, click Add Reference.
2. On the COM tab, click Browse.
3. Locate the folder that contains the Visual Basic 6.0 ActiveX DLL, and then click the DLL.
4. In the Selected Components list, click the DLL, and then click OK.

Delete the Module...End Module procedure, and then add the following code in the Module1 declarations section:

Module Module1
    Class Cls1
        Sub F()
            MsgBox("Hello")
        End Sub
    End Class

    Sub Main()
        Dim Obj As New Project1.Class1()    'Make sure that the ProgID matches the
                                            'legacy component that you created earlier.
        Dim Obj1 As Cls1                     
                                            
        Obj1 = New Cls1()
        Obj.LegacySub(Obj1)
    End Sub
End Module

Press F5 to run the project. Notice that you receive the error message that is listed in the "Symptoms" section.

Resolution

Modify the code in Module1 as follows:

Module Module1
    Sub Main()
        Dim Obj As New Project1.Class1()
        Dim Obj1 As Cls1

        Obj1 = New Cls1()
        Obj.LegacySub(Obj1)
    End Sub
End Module

Public Class Cls1
    Sub F()
        MsgBox("Hello")
    End Sub
End Class