If I remove the reference to the class library, the error disappear.
You need to have the Windows 10 source media with you.
The full command line would typically look something like this: SETUP.
We encourage you to try out our Visual Studio 2010 RC release which can be obtained from Option 2: If the two class libraries are different, split the "Windows Forms Application" project into two (one copy for each solution), so that each of the two versions of the windows forms application can depend on the correct Class Library.
The problem is not caused by a cross-solution project reference.
This could indicate that an incompatible app installed on your PC is blocking the upgrade process from completing.