Swashbuckle 5 can't find my ApiControllers

I got stuck.. and these answers didn't help me fully... although they led me there. Just to save other people some time:

You have to pass the http config from OWIN and then register on that instead of using the GlobalConfiguration class like so:

//starup.cs
public void Configuration(IAppBuilder app)
    {
        Config = new HttpConfiguration();
        WebApiConfig.Register(Config);

        app
            .UseResponseLogging()
            .UseRequestLogging()
            .UseHttpErrors()
            .UseExceptionLogging()
            .UseWebApi(Config);

        HandlerConfig.Register(Config);

        SwaggerConfig.Register(Config);
    }

and in the swagger config file, change the register method to:

public static void Register(HttpConfiguration config)
    {
        var thisAssembly = typeof(SwaggerConfig).Assembly;

        config
            .EnableSwagger(c =>
                {...

Hope this helps.

I found the problem. After creating an empty test project, I noticed that the WebApiConfiguration was being registered from the global.asax app start and not the OWIN startup class (like I did).

Since Swagger/Swashbuckle is hooking into the GlobalConfiguration and also given that OWIN startup and Global.asax live in different contexts (I think), the fix is to wire up your WebAPI stuff to register from Global.asax and to have OWIN's app object use WebAPI.

Relevant bits:

   // global asax
    protected void Application_Start(object sender, EventArgs e)
    {
        GlobalConfiguration.Configure(WebApiConfig.Register);
       // ... more stuff
    }

   //startup.cs
   public void Configuration(IAppBuilder app)
    {
        // This must happen FIRST otherwise CORS will not work.
        app.UseCors(CorsOptions.AllowAll);

        HttpConfiguration config = new HttpConfiguration();

        ConfigureAuth(app);

        // webapi is registered in the global.asax
        app.UseWebApi(config);

    }

After rewiring as above, I can now see controllers & actions in swagger UI.

I found that I had the same issue. I created an extension method to help

using Swashbuckle.Application;
using System.Web.Http;

public static class SwaggerExtensions
{
    public static HttpConfiguration EnableSwagger(this HttpConfiguration httpConfiguration)
    {
        httpConfiguration
            .EnableSwagger(c => c.SingleApiVersion("v1", "A title for your API"))
            .EnableSwaggerUi();
        return httpConfiguration;
    }
}

Then in my Startup.cs

public class Startup
{
    public void Configuration(IAppBuilder appBuilder)
    {
        HttpConfiguration httpConfiguration = new HttpConfiguration();

        httpConfiguration
            .EnableSwagger()    // <==== EXTENSION METHOD <==== //
            .MapHttpAttributeRoutes();

        httpConfiguration.Routes.MapHttpRoute(
            "DefaultApi",
            "api/{controller}/{id}",
            new {id = RouteParameter.Optional});

        appBuilder
            .UseWebApi(httpConfiguration);
    }
}