Debugging ASP.NET MVC
One of the handy things about ASP.NET MVC is that the source code is available. I’ve found this pretty useful over time when wanting to understand how things work. And occasionally it has been pretty helpful when trying to find out why my code isn’t working as it opens up the possibility of pulling in a local build of the official sources and stepping into it directly from my code! The process for doing this is quite simple (although not necessarily discoverable), so if you find yourself wanting to do this then check out David Ebbo’s blog post: Using a custom build of MVC 3.
Original post by Stuart Leeks on 07/03/2011 here: https://blogs.msdn.com/b/stuartleeks/archive/2011/03/07/debugging-asp-net-mvc.aspx