500 Error when setting up Swagger in asp .net CORE / MVC 6 app

If someone want to know the exact error is in the Swagger's stack trace, request the URL:

<your-app-url>/swagger/v1/swagger.json 

Or, click on the swagger.json link from the browser dev tools console:

Which will show the error in your IDE Output:

I got this error when one of my functions was marked as public, but wasn't meant to be a web service which could be called directly.

Changing the function to private made the error go away.

Alternatively, immediately before your public function, you can put the [NonAction] command, to tell Swagger to ignore it.

[NonAction] public async Task<IActionResult> SomeEvent(string id) { ... } 

(I wish Swagger would actually report the name of the function which caused this problem though, rather than just complaining that it could no longer find the "../swagger/v1/swagger.json" file... that's not particularly useful.)

Firstly you can enable the developer exception page by adding app.UseDeveloperExceptionPage(); on your Configure() in order to see better which is the root cause. Take a look here

In my case the problem was that I have to install also Microsoft.AspNetCore.StaticFiles nuget in order to make Swagger work.

Try also to uninstall/reinstall Swashbuckle.AspNetCore nuget.

I had this problem today and the cause was that some methods on my controllers API was missing [HttpGet]:

The exception (in stack trace) showed me the problme You can also check the exception in the Output window in Visual Studio like this (in my case it showed me):

In my case I was missing an action in route attribute which exist in your API controller.

Something like this:

[Route("api/[controller]/[action]")] 

Before I had:

[Route("api/[controller]")] 

An error occoures when writing [Route("api/[controller]")] because swagger doesn't know how to separate the API methods without action inside your route attribute.

1. Add [HttpGet] or [HttpPost] on top of api actions.

2. Add [Route("YourApiActionName")] on top of api actions ,

   or add [Route("[controller]/[action]")] on top of your Controller class.

Look here if you're not able to load the and look at the swagger.json in the console.

Swagger has a difficult time negotiating the differences between namespaces. When building the objects expected for api calls it will index through each defined class. If there are two classes that share a class name it won't be able to process the swagger.json file.

Example of two classes that .Net will process correctly, but Swagger will not.

namespace MyCompany.PaymentProcessor.DTO { public class Payment { //dto content } } 

and

namespace MyCompany.CbData { public class Payment { //couch base data } } 

Will be treated correctly by .Net, but unresolvable by swagger.

This came because you have a no-action method on your controller class check that missed an HTTP attribute on any of the controller action methods. If you need a no-action or no need for access from external methods declaration then make it private, you will fix this issue.

private void MyMethod() {

}

For swagger your API controller's all public method should be marked with [HttpGet/HttpPost/HttpPut/HttpDelete] or [NonAction] attribute.

If your controller is inheriting from ApiController, make sure your swagger is not complaining on ExecuteAsync method.

In this case you just need to override ExecuteAsync method in your controller and add [NonAction] attribute on it.

Had the same problem and the error message helped me identify the root cause:

{ "error": "Conflicting method/path combination \"POST api/calls\" for actions - SMSApi_v2.Controllers.CallController.CreateCall (SMSApi_v2),SMSApi_v2.Controllers.CallController.CreateCalls (SMSApi_v2). Actions require a unique method/path combination for Swagger/OpenAPI 3.0. Use ConflictingActionsResolver as a workaround" } 

The root were these lines of code:

 **[HttpPost("calls")]** public IActionResult CreateCall([FromBody]Call call) { repository.Create(call); return Ok(call); } **[HttpPost("calls")]** public IActionResult CreateCalls([FromBody] string xmlFile) { var calls = xmlProcessor.DeserializeTo<List<Call>>(xmlFile); if (!calls.Any()) return BadRequest("Deserializing was not done correctly."); repository.Create(calls); return Ok(calls); } 

Even if the signatures of the methods are different, the two API verbs have the same route and this is generating the error.

Might you've missed adding API verb to an endpoint. Can use below header as your need

1.[Microsoft.AspNetCore.Mvc.HttpGet] 2.[Microsoft.AspNetCore.Mvc.HttpPost] 

Also if I may add, the swagger set up does not like it when you route at the root level of your controllers. For example:

Do not do this:

[Produces("application/json")] [Route("/v1/myController")] [Authorize] public class myController { [SwaggerResponse((int)System.Net.HttpStatusCode.OK, Type = typeof(RestOkResponse<Response>))] [SwaggerResponse((int)System.Net.HttpStatusCode.InternalServerError, Type = typeof(RestErrorResponse))] [SwaggerResponse((int)System.Net.HttpStatusCode.BadRequest, Type = typeof(RestErrorResponse))] [SwaggerResponse((int)System.Net.HttpStatusCode.Forbidden, Type = typeof(RestErrorResponse))] [SwaggerResponse((int)System.Net.HttpStatusCode.NotFound)] [HttpPost] [Authorize()] public async Task<IActionResult> Create([FromBody] MyObject myObject) { return Ok(); } } 

Do this:

[Produces("application/json")] [Authorize] public class myController { [SwaggerResponse((int)System.Net.HttpStatusCode.OK, Type = typeof(RestOkResponse<Response>))] [SwaggerResponse((int)System.Net.HttpStatusCode.InternalServerError, Type = typeof(RestErrorResponse))] [SwaggerResponse((int)System.Net.HttpStatusCode.BadRequest, Type = typeof(RestErrorResponse))] [SwaggerResponse((int)System.Net.HttpStatusCode.Forbidden, Type = typeof(RestErrorResponse))] [SwaggerResponse((int)System.Net.HttpStatusCode.NotFound)] [HttpPost("/v1/myController")] [Authorize()] public async Task<IActionResult> Create([FromBody] MyObject myObject) { return Ok(); } } 

It took me a while to figure that the reason why I was getting internal server error was because of this routing issue. Hope this helps someone!

Might be obvious but, besides missing the HttpGet or HttpPost attributes, don't forget to differentiate the post methods.

You may have 2 different methods (with different names) marked with HttpPost, and that would also cause this kind of issue. Remember to specify the method name in the attribute: [HttpPost("update")].

in some cases, the router of controller is duplicated. Review the last controller modified.

Since I don't see the solution which worked for me posted here, I will contribute one to the ongoing thread. In my case, it was the Route attribute was set separately with the HttpPost/HttpGet at the function level (not controller level).

INCORRECT:

[HttpPost] [Route("RequestItem/{itemId}")] 

CORRECT:

[HttpPost("RequestItem/{itemId}")] 

Also, the Swagger seems to expect Ok(object) result instead of StatusCode(object) result for a success request to return.

I get same error in ASP.NET Boilerplate. I searched a lot and found a problem with my code. I use same name two DTO object, but located different namespaces.

For example first DTO object is like as below:

namespaces Test{ public class TestDto { public int Id{get;set;} } } 

And second DTO object is like as below:

namespaces Test_2{ public class TestDto { public int Id{get;set;} } } 

I changed Test_2.TestDto's name, problem did solve for me after.

In my case, a model has the same name as another model, I fixed changing the name

Give a look at this project. https://github.com/domaindrivendev/Ahoy/tree/master/test/WebSites/Basic

This repo is from Swashbuckle´s owner, is a basic ASP.NET 5 Sample app, this is help you to correct configure yours middlewares (and take care about the orders of them, it´s matter, e.g., use "app.UseSwaggerGen();app.UseSwaggerUi(); after app.UseMvc();)

To enable logging in your applcation give a look at: https://docs.asp.net/en/latest/fundamentals/logging.html?highlight=logging (the log will be generated inside "wwwroot" folder

When I Add the parameter Version , it works

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

Also had this problem. In my case, it was caused by two endpoints in the same controller with the same route and method name (but different parameter types). Of course, it then became apparent that that was probably poor practice anyway so I changed the endpoint names and all was well.

I was getting this error because in STARTUP.CS I not put the version's name in SwaggerDoc parameters:

Error => c.SwaggerDoc("", blablabla

WORK => c.SwaggerDoc("v1",blablabla

then, now are ok fine!

services.AddSwaggerGen(c => { c.SwaggerDoc("v1", new Swashbuckle.AspNetCore.Swagger.Info {Title = "PME SERVICES", Version = "v1"}); }); 

I ran into this issue today configuring Swagger in a .Net Core 2.2 Web Api project. I started down the path that @Popa Andrei mentions above by including the Microsoft.AspNetCore.StaticFiles dependency in my project as I figured that was most likely the culprit. That turned into a rabbit hole of chaining dependencies although it did ultimately work for me.

I then realized that in my ConfigureServices method in Startup I had services.AddMvcCore(...) which just gives you bare bones and you add dependencies as you need them. When I changed that to services.AddMvc(...) it started working without having to manually add all the dependencies required by Microsoft.AspNetCore.StaticFiles.

That doesn't mean you can't take the route of staying with services.AddMvcCore(...) and then adding all the necessary dependencies. You can, and it will work.

It is just much easier to take the services.AddMvc(...) approach and be done.

Hope that helps someone.

Making sure my swagger versions lined up with each other fixed my issue. Since I was starting a new project I set my api version to be v0.1

services.AddSwaggerGen(c => { c.SwaggerDoc("v0.1", new Info { Title = "Tinroll API", Version = "v0.1" }); }); 

But had left my swagger url to be v1.

app.UseSwaggerUI(c => { c.SwaggerEndpoint("/swagger/v1/swagger.json", "Tinroll API v0.1"); c.RoutePrefix = string.Empty; }); 

I updated my versioning to be /swagger/v0.1/swagger.json instead of v1 and Swagger worked as expected.

For me it was because of having two class types with the same name but with different namespaces, which are used as the return type of two different actions in different controllers!

When I changed the name of one of them, the problem solved!

For me the problem was due to OData. If I just commented out my services.AddOData(); I didn't get any error.just comment out the services.AddOData();

If you use Swagger, which is enabled by default in .Net Core 5, it needs to know something about your methods. Normally, you don't need to add [HttpGet] attribute because it is the default HttpMethod for your methods, but swagger requires that information to generate documentation of your code.

So adding [HttpGet] above my method solved my issue.

Error 500: http://localhost:4405/swagger/v1/swagger.json 

This error can occur when there are multiple endpoints, for example, two endpoints in the same controller with the [HttpPost] annotation. When this happens, it is necessary to differentiate them, using for example [HttpPost] on one and [HttpPost("User")] on the other.

I faced the same error and i found that i forget [HttpGet] annotation

The setup for Swagger is varying greatly from version to version. This answer is for Swashbuckle 6.0.0-beta9 and Asp.Net Core 1.0. Inside of the ConfigureServices method of Startup.cs, you need to add -

 services.AddSwaggerGen(c => { c.SingleApiVersion(new Info { Version = "v1", Title = "My Awesome Api", Description = "A sample API for prototyping.", TermsOfService = "Some terms ..." }); }); 

Then in the Configure method you must add -

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory) { loggerFactory.AddConsole(Configuration.GetSection("Logging")); loggerFactory.AddDebug(); app.UseMvc(); app.UseSwaggerGen(); app.UseSwaggerUi(); } 

Be sure you are referencing in Startup.cs -

using Swashbuckle.SwaggerGen.Generator;

My project.json file looks like -

"dependencies": { "Microsoft.AspNetCore.Mvc": "1.0.0-rc2-final", "Microsoft.AspNetCore.Server.IISIntegration": "1.0.0-rc2-final", "Microsoft.AspNetCore.Server.Kestrel": "1.0.0-rc2-final", "Microsoft.EntityFrameworkCore.SqlServer": "1.0.0-rc2-final", "Microsoft.EntityFrameworkCore.SqlServer.Design": "1.0.0-rc2-final", "Microsoft.EntityFrameworkCore.Tools": "1.0.0-*", "Microsoft.Extensions.Configuration.EnvironmentVariables": "1.0.0-rc2-final", "Microsoft.Extensions.Configuration.FileExtensions": "1.0.0-rc2-final", "Microsoft.Extensions.Configuration.Json": "1.0.0-rc2-final", "Microsoft.Extensions.Logging": "1.0.0-rc2-final", "Microsoft.Extensions.Logging.Console": "1.0.0-rc2-final", "Microsoft.Extensions.Logging.Debug": "1.0.0-rc2-final", "Swashbuckle": "6.0.0-beta9" }, "tools": { "Microsoft.AspNetCore.Server.IISIntegration.Tools": { "version": "1.0.0-preview1-final", "imports": "portable-net45+win8+dnxcore50" }, "Microsoft.EntityFrameworkCore.Tools": { "version": "1.0.0-preview1-final", "imports": [ "portable-net45+win8+dnxcore50", "portable-net45+win8" ] } }, "frameworks": { "net452": { } }, "buildOptions": { "emitEntryPoint": true, "preserveCompilationContext": true, "xmlDoc": false }, "publishOptions": { "include": [ "wwwroot", "Views", "appsettings.json", "web.config" ] }, "scripts": { "postpublish": [ "dotnet publish-iis --publish-folder %publish:OutputPath% --framework %publish:FullTargetFramework%" ] } }