¿Why is Blend and Visual studio 12 throwing and exception?
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Hi I'm using some UserControls with empty logic in the constructor and they are throwing an exception. I don't get whats happening. All my user controls worked before the reléase candidate, in the developer preview, but after som adjustments to work on the RC the user controls refuse to be shown. The code runs perfectly but I cannot design properly.

     {
            this.InitializeComponent();
     }

![enter image description here][1]


  [1]: http://i.stack.imgur.com/11prt.jpg