ASP.NET Core - Swashbuckle not creating swagger.json file

I am having trouble getting the Swashbuckle.AspNetCore (1.0.0) package to generate any output. I read the swagger.json file should be written to '~/swagger/docs/v1'. However, I am not getting any output.

I started with a brand new ASP.NET Core API project. I should mention this is ASP.NET Core 2. The API works, and I am able to retrieve values from the values controller just fine.

My startup class has the configuration exactly as described in this article (Swashbuckle.AspNetCore on GitHub).

public class Startup
{
    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }

    public IConfiguration Configuration { get; }

    // This method gets called by the runtime. Use this method to add services to the container.
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc();

        services.AddSwaggerGen(c =>
        {
            c.SwaggerDoc("v1", new Info { Title = "My API", Version = "v1" });
        });
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();

            // Enable middleware to serve generated Swagger as a JSON endpoint.
            app.UseSwagger();
            app.UseSwaggerUI(c =>
            {
                c.SwaggerEndpoint("/swagger/v1/swagger.json", "MyAPI V1");
            });
        }
        else
        {
            app.UseExceptionHandler();
        }

        app.UseStatusCodePages();
        app.UseMvc();

        //throw new Exception();
    }
}

You can see the NuGet references...

Again, this is all the default template, but I include the ValuesController for reference...

[Route("api/[controller]")]
public class ValuesController : Controller
{
    // GET api/values
    [HttpGet]
    public IEnumerable<string> Get()
    {
        return new string[] { "value1", "value2" };
    }

    // GET api/values/5
    [HttpGet("{id}")]
    public string Get(int id)
    {
        return "value";
    }

    // POST api/values
    [HttpPost]
    public void Post([FromBody]string value)
    {
    }

    // PUT api/values/5
    [HttpPut("{id}")]
    public void Put(int id, [FromBody]string value)
    {
    }

    // DELETE api/values/5
    [HttpDelete("{id}")]
    public void Delete(int id)
    {
    }
}

I believe you missed these two lines on your Configure:

if (env.IsDevelopment())
{
    app.UseDeveloperExceptionPage();

    // Enable middleware to serve generated Swagger as a JSON endpoint.
    app.UseSwagger();
    app.UseSwaggerUI(c =>
    {
        c.SwaggerEndpoint("/swagger/v1/swagger.json", "MyAPI V1");
    });
}

To access Swagger UI, the URL should be: http://localhost:XXXX/swagger/

The json can be found at the top of Swagger UI:

Sukhminder Sandhu

#if DEBUG
   // For Debug in Kestrel
   c.SwaggerEndpoint("/swagger/v1/swagger.json", "Web API V1");
#else
   // To deploy on IIS
   c.SwaggerEndpoint("/webapi/swagger/v1/swagger.json", "Web API V1");
#endif

When deployed to IIS webapi(base URL) is the Application Alias. You need to keep Application Alias(base URL) same for all IIS deployments because swagger looks for swagger.json at "/swagger/v1/swagger.json" location but wont prefix application Alias(base URL) that is the reason it wont work.

For Example:

localhost/swagger/v1/swagger.json - Couldn't find swagger.json

I had the same problem. Check http://localhost:XXXX/swagger/v1/swagger.json. If you get any a errors, fix them.

For example, I had an ambiguous route in a base controller class and I got the error: "Ambiguous HTTP method for action. Actions require an explicit HttpMethod binding for Swagger 2.0.". If you use base controllers make sure your public methods use the HttpGet/HttpPost/HttpPut/HttpDelete OR Route attributes to avoid ambiguous routes.

Then, also, I had defined both HttpGet("route") AND Route("route") attributes in the same method, which was the last issue for swagger.

Paweł Zieliński

If your application is hosted on IIS/IIS Express try the following:

c.SwaggerEndpoint("../swagger/v1/swagger.json", "MyAPI V1");

I was running into a similar, but not exactly the same issue with swagger. Hopefully this helps someone else.

I was using a custom document title and was not changing the folder path in the SwaggerEndPoint to match the document title. If you leave the endpoint pointing to swagger/v1/swagger.json it won't find the json file in the swagger UI.

Example:

services.AddSwaggerGen(swagger =>
        {
            swagger.SwaggerDoc("AppAdministration", new Info { Title = "App Administration API", Version = "v1.0" });

        });


 app.UseSwaggerUI(c =>
        {
            c.SwaggerEndpoint("/swagger/AppAdministration/swagger.json", "App Administration");
        });

You must conform 2 rules:

Decorate all actions with explicit Http Methods like[HttpGet("xxx")],[HttpPost("xxx")] or ... instead of [Route("xxx")].
Decorate public methods in controllers with [NoAction] Attribute.

Note that http://localhost:XXXX/swagger/ page requests for http://localhost:XXXX/swagger/v1/swagger.json file, but an Exception will occur from Swagger if you wouldn't conform above rules.

After watching the answers and checking the recommendations i end up having no clue what was going wrong.

I literally tried everything.So guys if you end up in the same situation , understand that the issue might be something else , completely irrelevant from swagger.

In my case was a OData exception.

After you navigate to the localhost:xxxx/swagger open developer tools click on the error on the console and you will see the inner exception that is causing the issue.

Hope that helps

If you have any issues in your controller to map to an unique URL you get this error.

The best way to find the cause of issue is exclude all controllers from project. Then try running the app by enabling one controller or one or more methods in a controller at a time to find the controllers/ controller method(S) which have an issue. Or you could get smart and do a binary search logic to find the disable enable multiple controller/methods to find the faulty ones.

Some of the causes is

Having public methods in controller without HTTP method attributes
Having multiple methods with same Http attributes which could map to same api call if you are not using "[action]" based mapping

Personally I had the same issue and when I tried again today after a while I found in the new version (2.5.0) that going in the json I could see an explanation of the error that was in here.

Also another thing that helped to fix it to me was removing the hosting information connected to the website that is hold inside "..vs\config\applicationhost.config" at the root of the solution folder

I removed the element that was configuring the website.

           <site name="**" id="9">
              <application path="/" applicationPool=""></application>
              <bindings></bindings>
           </site>

A common error that we make when use Swagger is to give the same name to(NET ASP) two or more routes. this cause that swagger cannot generate the JSON file. for example, this is a wrong way

[HttpPost, Route("Start")]
public async Task<TransactionResult> WipStart(BodyWipStartDTO data)
{
    return await _wipServices.WipStart(data);
}

Other action with the same route name but different action name

[HttpPost, Route("Start")]
public async Task<TransactionResult> WipAbort(BodyWipStartDTO data)
{
    return await _wipServices.WipAbort(data);
}

This a correct way

[HttpPost, Route("Start")]
public async Task<TransactionResult> WipStart(BodyWipStartDTO data)
{
    return await _wipServices.WipStart(data);
}

[HttpPost, Route("Abort")]
public async Task<TransactionResult> WipAbort(BodyWipStartDTO data)
{
    return await _wipServices.WipAbort(data);
}

Try to follow these steps, easy and clean.

Check your console are you getting any error like "Ambiguous HTTP method for action. Actions require an explicit HttpMethod binding for Swagger 2.0."
If YES: Reason for this error: Swagger expects

each endpoint should have the method (get/post/put/delete)

. Solution:

Revisit your each and every controller and make sure you have added expected method.

(or you can just see in console error which controller causing ambiguity)

If NO. Please let us know your issue and solution if you have found any.

I have came across the same issue, and noticed that my API has not hosted in the root folder and in an virtual directory. I moved my API to the root folder in IIS and worked.