Although Expression Blend and Visual Studio can work on the same solution / project files, they remain two separate IDEs and it is not uncommon for certain functionality to work correctly in the Visual Studio design-time environment and throw an error in the Expression Blend one. The Blend error output does not always help much with identifying the reason for the erroneous behavior:


 This clearly does not give us enough information to track the problem down. Fortunately there is an easier way to detect the problem instead of wandering around the code in a manual “debugging” session – the Visual Studio debugger.

 Here is a step-by-step guide that explains how to identify Expression Blend exceptions through the Visual Studio 2008 IDE:

  • Open the same solution in both Expression Blend and Visual Studio 2008 (for the time being keep the offending xaml file closed).
  • Start the Visual Studio 2008 debugger.
  • In Visual Studio go to Debug menu –> Attach to Process…


  • Find the “Blend.exe” process in the list of available processes and make sure you will be debugging the “Managed Code” option before clicking the “Attach” button:
  • In Expression Blend open the problematic xaml file.
  • If everything is set up correctly, now you should be receiving the full stack trace and exception details in the Visual Studio 2008 IDE like this:



Hope this helps.

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