Seeing loads of ‘cannot load load assemblies’ errors when editing a TFS 2010 build process workflow

I have been following the process in the ALM Rangers build guide and in the Community Build Extensions to edit a build process workflow. Now I am sure this process was working until recently on my PC (but we all say that don’t we!), but of late I have found that when the .XAML workflow is loaded into Visual Studio I see loads of warning icons. If I check the list of imported namespaces many of them also have warning icons which if the icons are clicked they say the assembly cannot be found.

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Now all these errors did not stop the editing process working. What I found was that if I made an edit in the graphical designer for the workflow or edited a property of an activity then my Visual Studio instance locked for about 20 seconds and it was fine (whilst there was loads of disk activity). I also noticed I got no intellisense when setting properties. Not a great position to be in but at least I could make some edits, if only slowly.

Using Process Monitor I could see that Visual Studio was scanning folders for the files when loading the XAML workflow, but not finding them.

The fix is actually simple. In the project that is being used as a container for the workflow being editing, make sure you reference the missing assemblies. These can be found in one of the following folders

  • C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE
  • C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\PrivateAssemblies
  • C:\Program Files (x86)\Microsoft Visual Studio 10.0\Common7\IDE\ReferenceAssemblies\v2.0

On my PC most of the assemblies were in the ReferenceAssemblies folder, not the first two, but on checking another PC at my office they were present in the PrivateAssemblies (which VS does scan)

Not sure why this has stopped working, what removed the files from my PrivateAssemblies folder, the only thing I can thing that I did was to install the Dev11 preview, But can’t see how this should have any effect.