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

[hpjchobbes]

I am using a third party reference, which is a COM object. The COM object has an Open and Close function and I need to make sure that Close is always called whenever possible. I wrote a wrapper class that implements IDisposable and in the Dispose function, I try to call the Close function. However I get a System.Runtime.InteropServices.InvalidComObjectException when I try to call the close function with additional details of "COM object that has been separated from its underlying RCW cannot be used."

public class MyWrapper : IDisposable
{
private Session _mySession = new Session(); // This is the COM object

public void Open() { \_MySession.Open(); }
public void Close() { \_MySession.Close(); }

public void Dispose() {
    Dispose(true);
    GC.SuppressFinalize(this);
}

public void Dispose(bool disposing) {
    \_MySession.Close(); // Calling close without having called open is OK
}
~MyWrapper() { Dispose(false); }    

}

From my (limited) understanding, there are two reasons why I am getting the exception. 1) The Finalizer is running and calling the destructor, but because the finalizer is on a separate thread I get the error. 2) Based on this Stack Overflow[^] post, the Runtime Callable Wrapper (RCW) has it's own finalizer which is being called before mine, and getting rid of the COM object. I don't know if either of these, or both of these are true, but what is the recommended way to implement a COM object that needs to have finalizer code run?