protected void Application_Start() { AreaRegistration.RegisterAllAreas(); GlobalConfiguration.Configure(WebApiConfig.Register); FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters); RouteConfig.RegisterRoutes(RouteTable.Routes); BundleConfig.RegisterBundles(BundleTable.Bundles); var xmlFormatter = new NamespacedXmlMediaTypeFormatter() { UseXmlSerializer = true }; xmlFormatter.Namespaces.Add("cla", "http://www.test.com/examples/claim"); GlobalConfiguration.Configuration.Formatters.Insert(0, xmlFormatter); //GlobalConfiguration.Configuration.Formatters.Clear(); //GlobalConfiguration.Configuration.Formatters.Add(new System.Net.Http.Formatting.XmlMediaTypeFormatter()); // GlobalConfiguration.Configuration.Formatters.Insert(0, new ClaimMediaTypeFormatter()); // GlobalConfiguration.Configuration.Formatters.JsonFormatter.UseDataContractJsonSerializer = false; }