I have a Class Library project in .NET Core named “LIBTOOBA” with the following setup:

Project File (LIBTOOBA.csproj):

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <TargetFramework>net6.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
    <PlatformTarget>AnyCPU</PlatformTarget>
  </PropertyGroup>

  <ItemGroup>
    <Reference Include="Interop.TSMSLIB_TLB">
      <HintPath>DLLSInterop.TSMSLIB_TLB.dll</HintPath>
      <EmbedInteropTypes>True</EmbedInteropTypes>
    </Reference>
  </ItemGroup>

</Project>

Details about the DLL:

• Name: Interop.TSMSLIB_TLB
• Works on Platform target: x86

Class Definitions:

namespace LIBTOOBA
{
    class Authentication
    {
        //...
    }

    class Proxy
    {
        //...
    }

    using TSMSLIB_TLB;

    class TSMS
    {
        private Authentication a = new Authentication();
        public Authentication A
        {
            set { this.a = value; }
            get { return this.a; }
        }

        private TSMS_Tooba t = new TSMS_Tooba();
        public TSMS_Tooba T
        {
            set { this.t = value; }
            get { return this.t; }
        }

        public void init()
        {
            t.UserName = this.a.UserName;
            t.Password = this.a.PassWord;
            t.LibKey = this.a.LibKey;
            t.ProxyServer = this.p.Server;
            t.ProxyPort = this.p.Port;
            t.ProxyUserName = this.p.UserName;
            t.ProxyPassword = this.p.PassWord;
        }
    }
}

Main Class:

namespace LIBTOOBA
{
    public class CL_TOOBASMS
    {
        private readonly TSMS CL_SMS;

        public CL_TOOBASMS(string userName, string password, string libKey)
        {
            // Validate inputs
            if (string.IsNullOrWhiteSpace(userName))
                throw new ArgumentException("Username cannot be null or empty", nameof(userName));
            if (string.IsNullOrWhiteSpace(password))
                throw new ArgumentException("Password cannot be null or empty", nameof(password));
            if (string.IsNullOrWhiteSpace(libKey))
                throw new ArgumentException("LibKey cannot be null or empty", nameof(libKey));

            CL_SMS = new TSMS();

            try
            {
                CL_SMS.A.UserName = userName;
                CL_SMS.A.PassWord = password;
                CL_SMS.A.LibKey = libKey;
            }
            catch (Exception ex)
            {
                throw new InvalidOperationException("Failed to set SMS library credentials.", ex);
            }
        }

        public (string Number, int Credit, int UsedCredit, string LastDate) GetMyAccountInfo()
        {
            //...
            return (number, credit, usedCredit, lastDate);
        }

        public string GetDeliveryInfo(string sendToNumber, string sendEvent)
        {
            //...
            return delivery;
        }

        public string SendSMS(string sendToNumber, string sendMsg)
        {
            //...
            return sendEventTxt;
        }
    }
}

My Issue:
I have a WPF .NET Core 6 Application with Platform target set to AnyCPU (x64). When I add the “LIBTOOBA” library and try to run the application, I get the following error:

System.Runtime.InteropServices.COMException: 'Retrieving the COM class factory for component with CLSID {83A108DD-D51F-43AF-9290-00541698F0F9} failed due to the following error: 80040154 Class not registered (0x80040154 (REGDB_E_CLASSNOTREG)).'

There is no x64 version of the Interop.TSMSLIB_TLB.dll.

If I change my WPF Platform target to x86, it runs successfully. However, I want to keep my WPF .NET Core 6 Application on Platform target AnyCPU (x64). How can I bypass this issue?

Potential Solutions I am Considering:

• “Side-by-side” COM activation: Load the 32-bit COM component in a 64-bit process
• PInvoke (Platform Invoke) to call functions directly from unmanaged DLLs
• Separate 32-bit process for COM Interop
• Use CorFlags to force x86 execution
• Create a C++/CLI wrapper

Any suggestions or guidance on how to implement one of these solutions or another approach would be greatly appreciated.

I want to keep my WPF .NET Core 6 Application on Platform target AnyCPU (x64) , How can I bypass that ?