Always If you are using SIM to create your Sitecore visual studio solution, you will get the following structure:
I am using SIM 18.104.22.1683 with Sitecore 8.2 – Update 2
When you try to add a controller or an area in your project, you might see the following error:
On looking this up, many results seem to suggest clearing temporary asp.net files at C:\WINDOWS\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\
This didnt work for me.
On looking further, this issue seemed to be caused because web.config is not included in the project by default.
Include the web.config in your project all is good! Always ensure your web.config is available in your solution and is valid when you encounter a similar error.