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WPF Thread: "A COM object that has been separated from its base RCW cannot be used."

I get the following error:

"COM object that has been separated from its underlying RCW cannot be used."

I am sure that the problem is that the COM object is not called in the thread that was created - STA. I tried to implement IDisposable, but it did not work for me.

There are several posts devoted to a similar problem, but which still do not solve my problem:

Is it safe to call RCW from the finalizer? Release the Excel object in my destructor

Can someone post an example / explain how a COM object should be correctly accessible from another thread?

Here is the minimal code that shows the problem:

using System;
using System.Threading;

namespace Test.ComInterop
{
    public class Program
    {
        MyCom _myCom;

        [STAThread]
        static void Main( string[] args )
        {
            new Program();
        }

        public Program()
        {
            _myCom = new MyCom();

            // this method call works
            string version = _myCom.ComMethod();

            StartThread();
        }

        private void StartThread()
        {
            Thread t = new Thread( UIRun );
            t.SetApartmentState( ApartmentState.STA );
            t.Start();
        }

        void UIRun()
        {
            TestUI window = new TestUI();
            window.Show();

            // this method call fails
            window.Title = _myCom.ComMethod();

            window.Closed += ( sender2, e2 ) 
                => window.Dispatcher.InvokeShutdown();

            System.Windows.Threading.Dispatcher.Run();
        }
    }

    class MyCom
    {
        private dynamic _com;
        public MyCom()
        {
            _com = Activator.CreateInstance(
                Type.GetTypeFromProgID( "Excel.Application" ) );
        }

        public string ComMethod()
        {
            return (string) _com.Version;
        }
    }    
}
0
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MTA?

+2

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+1

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+1

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