Intermittent Error (System.TypeInitializationExcep

问题:

WE have a WPF application which will launch a word and then pass some information to a VSTO Application addin.

I have written the code as has been explained here

We defined the interface and the implemtation as follows

[ComVisible(true)]
[Guid("B523844E-1A41-4118-A0F0-FDFA7BCD77C9")]
[InterfaceType(ComInterfaceType.InterfaceIsDual)]
public interface IBridge {      
    /// <summary>
    /// Loads a task 
    /// </summary>      
    /// <returns> </returns>
    string Load(SomeDTO dataTransferObject);
     }

     [ComVisible(true)]
[ClassInterface(ClassInterfaceType.None)]
public class ConcreteBridge : StandardOleMarshalObject, IBridge {
    public ConcreteBridge() { }
            public string Load(SomeDTO dataTransferObject) {
            return "some value";
            }
     }

Now I am trying to access the addin

object addInName = addinName;
COMAddIn addIn =   WordApp.COMAddIns.Item(ref addInName);
return (IBridge)addIn.Object;

The application works just fine most of the time. However , some times it throws below exception.

System.TypeInitializationException: Type constructor threw an exception. at Utilities.IBridge.Load(SomeDTO dataTransferObject)

I am not sure why this happens and would appreciate if anybody could guide me.