Upgraded Visual Studio and receive build error "Type 'Desktop' is not defined"
Issue was caused by a Visual Studio configuration issue in the project. Known Visual Studio issue reported online.
You need to make sure that the consuming project is targeting a .NET Framework version which is equal to or higher than the other project that it is referencing. If the referenced project is targeting a higher version of the framework, Visual Studio will not give you a useful message like, "Wrong Framework Version".
Setting the Target Framework to the latest version and rebuilding the solution/project resolves the issue.
1. Open the properties of the project
2. Set the Target Framework to your highest version.
3. Rebuild the Solution/Project.