How to return HTTP 500 from ASP.NET Core RC2 Web Api?

Back in RC1, I would do this:

[HttpPost]
public IActionResult Post([FromBody]string something)
{    
    try{
        // ...
    }
    catch(Exception e)
    {
         return new HttpStatusCodeResult((int)HttpStatusCode.InternalServerError);
    }
}

In RC2, there no longer is HttpStatusCodeResult, and there is nothing I can find that lets me return a 500 type of IActionResult.

Is the approach now entirely different for what I'm asking? Do we no longer try-catch in Controller code? Do we just let the framework throw a generic 500 exception back to the API caller? For development, how can I see the exact exception stack?

From what I can see there are helper methods inside the ControllerBase class. Just use the StatusCode method:

[HttpPost]
public IActionResult Post([FromBody] string something)
{    
    //...
    try
    {
        DoSomething();
    }
    catch(Exception e)
    {
         LogException(e);
         return StatusCode(500);
    }
}

You may also use the StatusCode(int statusCode, object value) overload which also negotiates the content.

You could use Microsoft.AspNetCore.Mvc.ControllerBase.StatusCode and Microsoft.AspNetCore.Http.StatusCodes to form your response, if you don't wish to hardcode specific numbers.

return  StatusCode(StatusCodes.Status500InternalServerError);

UPDATE: Aug 2019

Perhaps not directly related to the original question but when trying to achieve the same result with Microsoft Azure Functions I found that I had to construct a new StatusCodeResult object found in the Microsoft.AspNetCore.Mvc.Core assembly. My code now looks like this;

return new StatusCodeResult(StatusCodes.Status500InternalServerError);

If you need a body in your response, you can call

return StatusCode(StatusCodes.Status500InternalServerError, responseObject);

This will return a 500 with the response object...

For aspnetcore-3.1, you can also use Problem() like below;

https://docs.microsoft.com/en-us/aspnet/core/web-api/handle-errors?view=aspnetcore-3.1

 [Route("/error-local-development")]
public IActionResult ErrorLocalDevelopment(
    [FromServices] IWebHostEnvironment webHostEnvironment)
{
    if (webHostEnvironment.EnvironmentName != "Development")
    {
        throw new InvalidOperationException(
            "This shouldn't be invoked in non-development environments.");
    }

    var context = HttpContext.Features.Get<IExceptionHandlerFeature>();

    return Problem(
        detail: context.Error.StackTrace,
        title: context.Error.Message);
}

A better way to handle this as of now (1.1) is to do this in Startup.cs's Configure():

app.UseExceptionHandler("/Error");

This will execute the route for /Error. This will save you from adding try-catch blocks to every action you write.

Of course, you'll need to add an ErrorController similar to this:

[Route("[controller]")]
public class ErrorController : Controller
{
	[Route("")]
	[AllowAnonymous]
	public IActionResult Get()
	{
		return StatusCode(StatusCodes.Status500InternalServerError);
	}
}

More information here.

---

In case you want to get the actual exception data, you may add this to the above Get() right before the return statement.

// Get the details of the exception that occurred
var exceptionFeature = HttpContext.Features.Get<IExceptionHandlerPathFeature>();

if (exceptionFeature != null)
{
    // Get which route the exception occurred at
    string routeWhereExceptionOccurred = exceptionFeature.Path;

    // Get the exception that occurred
    Exception exceptionThatOccurred = exceptionFeature.Error;

    // TODO: Do something with the exception
    // Log it with Serilog?
    // Send an e-mail, text, fax, or carrier pidgeon?  Maybe all of the above?
    // Whatever you do, be careful to catch any exceptions, otherwise you'll end up with a blank page and throwing a 500
}

Above snippet taken from Scott Sauber's blog.

return StatusCode((int)HttpStatusCode.InternalServerError, e);

Should be used in non-ASP.NET contexts (see other answers for ASP.NET Core).

HttpStatusCode is an enumeration in System.Net.

How about creating a custom ObjectResult class that represents an Internal Server Error like the one for OkObjectResult? You can put a simple method in your own base class so that you can easily generate the InternalServerError and return it just like you do Ok() or BadRequest().

[Route("api/[controller]")]
[ApiController]
public class MyController : MyControllerBase
{
    [HttpGet]
    [Route("{key}")]
    public IActionResult Get(int key)
    {
        try
        {
            //do something that fails
        }
        catch (Exception e)
        {
            LogException(e);
            return InternalServerError();
        }
    }
}

public class MyControllerBase : ControllerBase
{
    public InternalServerErrorObjectResult InternalServerError()
    {
        return new InternalServerErrorObjectResult();
    }

    public InternalServerErrorObjectResult InternalServerError(object value)
    {
        return new InternalServerErrorObjectResult(value);
    }
}

public class InternalServerErrorObjectResult : ObjectResult
{
    public InternalServerErrorObjectResult(object value) : base(value)
    {
        StatusCode = StatusCodes.Status500InternalServerError;
    }

    public InternalServerErrorObjectResult() : this(null)
    {
        StatusCode = StatusCodes.Status500InternalServerError;
    }
}

When you want to return a JSON response in MVC .Net Core You can also use:

Response.StatusCode = (int)HttpStatusCode.InternalServerError;//Equals to HTTPResponse 500
return Json(new { responseText = "my error" });

This will return both JSON result and HTTPStatus. I use it for returning results to jQuery.ajax().

The built-in Problem()-method of Microsoft.AspNetCore.Mvc will return a "problem detail"-response based on RFC 7807 (in ASP.NET Core 3.0 and later). It will always return status-code 500 as long as no other status is explicitly set.

[HttpPost]
public IActionResult Post([FromBody] string value)
{
    try
    {
        // ...
    }
    catch (Exception ex)
    {
        return Problem(
        	//all parameters are optional:
            //detail: "Error while processing posted data."; //an explanation, ex.Stacktrace, ...
            //instance: "/city/London"  //A reference that identifies the specific occurrence of the problem
            //title: "An error occured." //a short title, maybe ex.Message
			//statusCode: StatusCodes.Status504GatewayTimeout, //will always return code 500 if not explicitly set
			//type: "http://example.com/errors/error-123-details"  //a reference to more information
            );
    }           
}

Without setting any parameters it will return this:

{
    "type": "https://tools.ietf.org/html/rfc7231#section-6.6.1",
    "title": "An error occured while processing your request.",
    "status": 500,
    "traceId": "|fadaed95-4d06eb16160e4996."
}

More infos about "problem details" parameters: https://docs.microsoft.com/en-us/dotnet/api/microsoft.aspnetcore.mvc.problemdetails?view=aspnetcore-5.0

For API Responses (using net core), I have tried this and seems that it is working fine:

var err = Content(JsonConvert.SerializeObject(response, SerializerSettings), "application/x-javascript", contentEncoding: System.Text.Encoding.UTF8);
err.StatusCode = StatusCodes.Status500InternalServerError;
return err;

You just need to create a response object first, then respond this. Doing this, we can retain the content type, encoding, and add a status code as well.

Just adding this for future reference to anybody who is stuck as well and wants a quick and easy way to do this.