Ensure that HttpConfiguration.EnsureInitialized() is called in the application's startup
This error prompts you when you forget to initialize the apllication startup to fix this problem kindly use the given below line and add it under global.asax file of solution.
GlobalConfiguration.Configuration.EnsureInitialized();
This is the complete stack trace which comes when you run an application.
<Error>
<Message>An error has occurred.</Message>
<ExceptionMessage>
The object has not yet been initialized. Ensure that HttpConfiguration.EnsureInitialized() is called in the application's startup code after all other initialization code.
</ExceptionMessage>
<ExceptionType>System.InvalidOperationException</ExceptionType>
<StackTrace>
at System.Web.Http.Routing.RouteCollectionRoute.get_SubRoutes() at System.Web.Http.Routing.RouteCollectionRoute.GetRouteData(String virtualPathRoot, HttpRequestMessage request) at System.Web.Http.WebHost.Routing.HttpWebRoute.GetRouteData(HttpContextBase httpContext)
</StackTrace>
</Error>
Hope it will sort out your issue.
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