Routing error: No HTTP resource was found that matches the request URI

Question

I'm trying to make the API call

http://localhost:56578/v1/reports

to call my GetReports() method.

However I continue to get the error message in the subject.

I'm following the ms docs here via the route prefix:

https://docs.microsoft.com/en-us/aspnet/web-api/overview/web-api-routing-and-actions/attribute-routing-in-web-api-2#route-prefixes

What am I doing wrong?

ReportV1Controller.cs

[Authorize]
[RoutePrefix("v1/reports")]
....
....
[Route("")]
public IHttpActionResult GetReports()

WebApiConfig.cs

config.Routes.MapHttpRoute(
    name: "DefaultApi",
    routeTemplate: "api/{controller}/{action}/{id}",
    defaults: new { id = RouteParameter.Optional }
);

Answer 1

Change from this:

[RoutePrefix("v1/reports")]

to this:

[RoutePrefix("api/v1/reports")]

because of:

config.Routes.MapHttpRoute(
        name: "DefaultApi",
        routeTemplate: "api/{controller}/{action}/{id}",
        defaults: new { id = RouteParameter.Optional }
    );

See routeTemplate: "api/{controller}/{action}/{id}" , you said prefix for all paths will be api , {controller}/{action}/{id} are placeholders

Conclusion: if you are going to use v1 prefix everywhere, put it instead of api

Answer 2

What you have should work provided that you have enabled attribute routing in the WebApiConfig

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        // Attribute routing.
        config.MapHttpAttributeRoutes(); //<-- THIS HERE

        // Convention-based routing.
        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "api/{controller}/{action}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );
    }
}

Reference Attribute Routing in ASP.NET Web API 2: Enabling Attribute Routing

And assuming

[Authorize]
[RoutePrefix("v1/reports")]
public class ReportV1Controller : ApiController {

    //GET v1/reports
    [Route("")]
    [HttpGet]
    public IHttpActionResult GetReports() {
        //...
    }
}