Problem: "Mapping URI" errors with WPF Assembly Names that include spaces

This is a somewhat insidious bug. As it turns out, if you have spaces in your WPF project’s assembly name, you can get “Mapping URI” errors in your project’s XAML (even if the solution itself builds properly). As you might imagine, you can get around this bug by changing the namespace. For example:

Change this:

OakLeaf MM WPF



Kevin McNeish
Microsoft .NET MVP
INETA Speaker
Chief Architect, MM .NET Application Framework

Getting Expression Blend to Launch VS 2008

If you have multiple versions of Visual Studio on your development machine, Expression Blend may launch the older version (for example, VS 2005) rather than VS 2008. To get Expression Blend to launch VS 2008, follow these steps:


  1. Run the Windows Registry Editor by launching a Command Prompt window (Windows Key + R), entering regedit and pressing ENTER.


  2. Navigate to HKEY_CLASSES_ROOT\VisualStudio.DTE.9.0\CLSID. In the right pane, double-click the (Default) value to edit it. In the Edit String dialog, copy the Value data into the paste buffer.


  3. Now navigate to HKEY_CLASSES_ROOT\VisualStudio.DTE\CLSID, edit the (Default) value, paste the value you copied over the existing value, and click OK to save it.


  4. If Expression Blend is running, exit and restart it. Now it should open VS 2008 when it needs to launch Visual Studio.