Migrating an MVC 5 project to ASP.NET 5 and MVC 6 is a big challenge given that both of the latter are complete rewrites of their predecessors. As a result, even if on the surface things seem similar (we have controllers, filters, actions etc), as you go deeper under the hood you realize that most, if not all, of your pipeline customizations will be incompatible with the new framework.
This pain is even more amplified if you try to migrate Web API 2 project to MVC 6 – because Web API had a bunch of its own unique concepts and specialized classes, all of which only complicate the migration attempts.
ASP.NET team provides an extra convention set on top of MVC 6, called “Web API Compatibility Shim”, which can be enabled make the process of migration from Web API 2 a bit easier. Let’s explore what’s in there.