C# calling C++ COM side by side error

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I would like to call a C++ COM dll from C# without having to register the COM object. I've read everything I can including closely following

Registration-Free Activation of COM Components: A Walkthrough

but I can't get it to work. It's fine if the C++ COM component is registered, but I get a "Library not registered. (Exception from HRESULT: 0x8002801D" if it's not.
C++ IDL (SideBySide.idl):

import "oaidl.idl";
import "ocidl.idl";

[
	object,
	uuid(40cd21b0-f634-4c41-88d6-b18fe881b86d),
	dual,
	nonextensible,
	helpstring("ISideBySideClass Interface"),
	pointer_default(unique)
]
interface ISideBySideClass : IDispatch
{
	[id(1)] HRESULT Version([out, retval] BSTR *pVer);
	[id(2)] HRESULT Output();
};
[
	uuid(604e4622-3763-47d9-b3ca-1d3190dcc7d2),
	version(1.0),
	helpstring("SideBySide 1.0 Type Library")
]
library SideBySideLib
{
	importlib("stdole2.tlb");
	[
		uuid(0cd09207-7bfa-41d3-aba6-d565c0fb00d2),
		helpstring("SideBySideClass Class")
	]
	coclass SideBySideClass
	{
		[default] interface ISideBySideClass;
	};
};

import "shobjidl.idl";

C# calling code (in Form1.cs):

Type myType = Type.GetTypeFromProgID("SideBySide.SideBySideClass.1");
dynamic obj = Activator.CreateInstance(myType);
obj.Output();  <==FAILS

C# EXE manifest (SideBySideCSharpExE.exe.manifest"):

<?xml version="1.0" encoding="utf-8"?>
<assembly manifestVersion="1.0"
       xmlns="urn:schemas-microsoft-com:asm.v1">
  <assemblyIdentity name="SideBySideCSharpExE.exe" version="1.0.0.0" type="win32" />
  <file name="SideBySide.dll">
    <comClass clsid="{0cd09207-7bfa-41d3-aba6-d565c0fb00d2}"
       threadingModel="Apartment"
       tlbid="{604e4622-3763-47d9-b3ca-1d3190dcc7d2}"
       progid="SideBySide.SideBySideClass.1"
       description="SideBySideClass Class" />
  </file>
  <comInterfaceExternalProxyStub name="ISideBySideClass"
      iid="{40cd21b0-f634-4c41-88d6-b18fe881b86d}"
      proxyStubClsid32="{40cd21b0-f634-4c41-88d6-b18fe881b86d}"
      baseInterface="{0cd09207-7bfa-41d3-aba6-d565c0fb00d2}"
      tlbid="{0cd09207-7bfa-41d3-aba6-d565c0fb00d2}"/>
</assembly>

Using
Visual Studio: 16.10.3
C++ Windows SDK: 10.0
C++ Platform Toolset: v142
C++ Language Standard: ISO C++ 14 Standard
Currently using Win32 since that's what the examples seem to be, but will want to use x64 in production code
C#: .NET Framework 4.7.2
Platform target: x86 (will want to move to x64)

What I have tried:

I've run sxstrace.exe, but it shows no errors, so I think the manifest file syntax is OK.
To create the manifest file I've tried both adding a reference in the C# project to the C++ project and compiling to get it and I've run regsvr42 on the C++ COM object.
I've set the C# property "Manifest:" to "Create application without a manifest" so it uses the external manifest, not an embedded one.

Posted 11-Aug-21 10:41am

blyon

Updated 13-Jan-22 12:50pm

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Comments

[no name] 11-Aug-21 17:40pm

https://docs.microsoft.com/en-us/dotnet/framework/interop/importing-a-type-library-as-an-assembly

blyon 11-Aug-21 19:42pm

That pointed me in the right direction.
Thanks

[no name] 13-Aug-21 11:09am

You're welcome!

KarstenK 17-Aug-21 9:00am

plz write answers as solution to close the q&a.

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blyon · Answer 1 · 2022-01-13T12:50:00

Solution 1

Changing the C# code in Form1.cs to:

C#

var sbsl = new SideBySideLib.SideBySideClass();
sbsl.Output();

fixed the problem.

Posted 13-Jan-22 12:50pm

blyon