Don't understand why we're getting error CS0234

In this case what I had to do was to delete everything in the obj folder beneath our project main folder. The solution's name is CoreFramework and the main project's name is also CoreFramework. So what I did was go to \CoreFramework\CoreFramework\obj and deleted everything there. Since at this point we're only dealing with a debug version, the only thing there was the Debug folder and all temporary files and folders under that. Once I did that, then rebuilding the solution re-created all of the temporary files and folders, without the problem I was having with the Assets folder. It built fine.

YMMV