问题
Since I am trying to recreate a legacy ASP.NET project rather than continue down the rabbit hole of trying to figure out why it gives me a no-clues-as-to-where-it-is "Object reference not set" error, I am trying to add the folders and files from the legacy solution - painstakingly, one at a time - and re/building after each addition to see where the error appears, if it does.
I made it partway, but then tried to add the "Common" folder which is below the "Bin" folder in the legacy project - but it won't let me:
There's no option afforded for adding a folder there. What can I do in order to proceed?
来源：https://stackoverflow.com/questions/40939639/is-it-not-possible-to-add-a-folder-to-an-asp-net-bin-folder