Episerver Routing Error ‘The routed data is of type..and the binding context data ... is of type ..., neither of which matches the requested type...’

Recently while trying to build an Episerver ecommerce solution I ran into an error with a type mismatch where navigating to any type of node or product failed with a type mismatch.

The ‘requested type’ for each product was always the same class.  I then noticed whenever a new type of product was added, the requested type was always the first type of model alphabetically.

The controller for each node and product type was inheriting from a base controller.

This turned out to be where the problem lay.  Each controller looked ok and seemed to be configured for the relevant model.

However, there was a typo in the inheritance on the base class here, which led to each controller compiling as ContentController<CatalogContentBase>.  Thus when processing the route, episerver was getting confused as to which model it should be resolving the route for, and just took a stab in the dark and grabbed the first model inheriting from CatalogContentBase it could find. 

Changing this to a type parameter constraint, so any class implementing this controller would have to be routing a model implementing catalogContentBase, fixed the error. 

Essentially if you run into this error, check that all your controllers are routing the correct content type, and if there is a base class, ensure this is also configured properly.