Hi James

The documentation is out of date :-(

GlobalSettings is marked as internal in the core and so you cannot access the UmbracoMvcArea property to add your custom route.

Also when you have right clicked and resolved your GlobalSettings class, it has found an older GlobalSetting class that is public from the older (lowercase u) umbraco namespace, and this does not contain the UmbracoMvcArea property which is why you are getting the specific error message.

If you read the umbracoPath property from the web.config this should I think give the correct location of the /umbraco folder to map your custom mvc route in the backoffice:

protected override void ApplicationStarted(UmbracoApplicationBase umbracoApplication, ApplicationContext
applicationContext)
        {
            var umbracoPath = System.Configuration.ConfigurationManager.AppSettings["umbracoPath"];
            if (umbracoPath.StartsWith(SystemDirectories.Root)) // beware of TrimStart, see U4-2518
                umbracoPath = umbracoPath.Substring(SystemDirectories.Root.Length);
            umbracoPath = umbracoPath.TrimStart('~').TrimStart('/').Replace('/', '-').Trim().ToLower();

            RouteTable.Routes.MapRoute(
            name: "cats",
            url: umbracoPath + "/backoffice/cats/{action}/{id}",
            defaults: new
            {
                controller = "Cats",
                action = "Meow",
                id = UrlParameter.Optional
            });
        }

Note it needs to have it's ~ and leading / removed...

When working with data in the backoffice, I tend to use an UmbracoAuthorizedJsonController or UmbracoAuthorizedApiController (as these are routed by convention) to expose data via Web Api endpoints, that I then consume in AngularJs, rather than creating an actual MVC controller for the backoffice, but I'm not sure what you are up to!! but the above should enable you to map the route correctly!

regards

Marc