ASP.NET MVC 5 ajax error statusText is always “error”

Question

I'm having a problem sending a custom message on error to an ajax call. My controller returns something like this:

return new HttpStatusCodeResult(400, "My error!");

And my ajax code looks like this:

error: function (xhr, httpStatusMessage) {
              console.log(xhr.statusText);
              console.log(httpStatusMessage);
}

The problem is that xhr.statusCode and httpStatusMessage is always "error". What am I doing wrong now? I'm expecting to have "My error!" in xhr.statusText.

I'm using ASP.NET MVC 5 and jquery-1.10.2

My xhr output is:

abort:ƒ ( statusText )
always:ƒ ()
complete:ƒ ()
done:ƒ ()
error:ƒ ()
fail:ƒ ()
getAllResponseHeaders:ƒ ()
getResponseHeader:ƒ ( key )
overrideMimeType:ƒ ( type )
pipe:ƒ ( /* fnDone, fnFail, fnProgress */ )
progress:ƒ ()
promise:ƒ ( obj )
readyState:4
responseText:"Bad Request"
setRequestHeader:ƒ ( name, value )
state:ƒ ()
status:400
statusCode:ƒ ( map )
statusText:"error"
success:ƒ ()
then:ƒ ( /* fnDone, fnFail, fnProgress */ )

My Web.config httpErrors configuration looks like this:

<httpErrors existingResponse="PassThrough" errorMode="Custom">
      <remove statusCode="404" />
      <error statusCode="404" path="/Error/NotFound" responseMode="ExecuteURL" />
      <remove statusCode="403" />
      <error statusCode="403" path="/Error/Forbidden" responseMode="ExecuteURL" />
    </httpErrors>

and still, on my dev environment, the responseText is empty and the statusText is just "error".

Answer 1

You need to set a property in your Web.Config file.

Citing a user of this web page on github, emphasis mine,

By default IIS will mask your error codes and replace them with default errors . The "PassThrough" option tells IIS to leave your custom errors alone and render them as-is.

"Bad Request" is the default http error text for the status code 400.

So there is the setting as documented here and outlined here ,

<configuration>
  <system.webServer>
    <httpErrors existingResponse="PassThrough"></httpErrors>
  </system.webServer>
</configuration>

Consult the documentation carefully for your version of IIS, there is lots of subtle version differences.

EDIT

Not really specific to MVC, but it is how I once solved it (part of production code), and what seems to have helped OP as well:

Response.TrySkipIisCustomErrors = true;
Response.StatusCode = (int)HttpStatusCode.InternalServerError;
Response.ContentType = "text/plain";
Response.Write(new String('_', 513) + "my custom message");

This absurd minimum character limit thing may or may not be needed depending on IIS version. I would too be grateful if somebody could shed a little more light on this underdocumented behavior.