title: Can't determine cause of CLR20r3 System.InvalidOperationException
body: <p>I have some experience debugging using Problem Signatures from uncaught exceptions, but this one is confusing to me. I'm running my application on a demo laptop to show to clients. It works perfectly on my dev machine.</p>
  
  <p>My application suddenly closes due to a <code>System.InvalidOperationException</code> in the <code>System.Core</code> framework assembly. I'm running the demo on a Dell Latitude E5420 With 8 GB or RAM, and Core i5-2520 @ 2.5GHz, on Windows 7 64-bit.</p>
  
  <p>The problem signature looks like this</p>
  
  <pre><code>Problem signature:
    Problem Event Name:   CLR20r3
    Problem Signature 01: asi.formsetcreation.exe
    Problem Signature 02: 1.0.0.0
    Problem Signature 03: 5411d2fd
    Problem Signature 04: System.Core
    Problem Signature 05: 4.0.30319.18408
    Problem Signature 06: 5231116c
    Problem Signature 07: 43f
    Problem Signature 08: 4d
    Problem Signature 09: System.InvalidOperationException
    OS Version:   6.1.7601.2.1.0.256.48
    Locale ID:    1033
    Additional Information 1: 0a9e
    Additional Information 2: 0a9e372d3b4ad19135b953a78882e789
    Additional Information 3: 0a9e
    Additional Information 4: 0a9e372d3b4ad19135b953a78882e789
  </code></pre>
  
  <p>The Problem Signature 04 shows me that the <code>System.Core</code> assembly is throwing the exception. The Problem Signature 07 (43f) shows me that the Method was the constructor of the <code>System.Security.Cryptography.ECDiffieHellmanCng</code> class</p>
  
  <pre><code>.method /*0600043F*/ private hidebysig specialname rtspecialname static 
          void  .cctor() cil managed
  {
    // Code size       0 (0x0)
  } // end of method ECDiffieHellmanCng::.cctor
  </code></pre>
  
  <p>The problem signature 08 (4d) shows me the IL offset within that method, which you can see doesn't exist in the method signature above.</p>
  
  <p>I have no idea what the <code>ECDiffieHellmanCng</code> class is. It is not used in my application, which is a WPF client application that makes service calls to a wcf forms processor service, and an asp.net hosted soap service.</p>
  
  <p>I hooked up to the <code>AppDomain.CurrentDomain.UnhandledException</code> handler, but it never handles the event, so I don't know what the stack trace of the exception is.</p>
  
  <p>Is there anything else I can try to find out what is using this <code>ECDiffieHellmanCng</code> class?</p>