500 Server Error HTML returned from MVC AJAX call when plain text specified

I am trying to return plain text from my MVC AJAX methods that indicates an error code. This is working fine on my dev machine, but when deployed to a server (Win2008 R2) I am always getting the HTML of the 500.htm page back in the error.responseText from my AJAX call instead of the text I specified. Any ideas why I would not get back the plain text I intended?

Here is my error handling logic in my controller.

    protected override void OnException(
        ExceptionContext filterContext
        )
    {
        try
        {
            Error error = ControllerCommon.ProcessException(filterContext);

            // return error
            filterContext.Result = HandleError(error.Type);
            filterContext.ExceptionHandled = true;
        }
        catch (Exception ex)
        {
            Logger.Instance.LogImportantInformation(ex.Message, 0, Constants.EventSourcePortal);
        }
    }

    #endregion

    #region Private Methods and Members

    private ActionResult HandleError()
    {
        return HandleError(Error.ErrorType.Unknown);
    }

    开发者_开发技巧private ActionResult HandleError(
        Error.ErrorType errorType
        )
    {
        // set return status code
        HttpContext.Response.StatusCode = (int)HttpStatusCode.InternalServerError;

        Logger.Instance.LogImportantInformation(((int)errorType).ToString(CultureInfo.InvariantCulture), 0, Constants.EventSourcePortal);

        // return error type
        return Content(((int)errorType).ToString(CultureInfo.InvariantCulture), "text/plain");
    }

Here is the header that I get back from the Server.

Response Headers Cache-Control private Content-Type text/html Server Microsoft-IIS/7.5 X-AspNet-Version 4.0.30319 X-Powered-By ASP.NET Date Mon, 20 Jun 2011 16:00:42 GMT Content-Length 1208 Request Headers Host pqompo2test01.dns.microsoft.com User-Agent Mozilla/5.0 (Windows NT 6.1; WOW64; rv:2.0.1) Gecko/20100101 Firefox/4.0.1 Accept text/html, / Accept-Language en-us,en;q=0.5 Accept-Encoding gzip, deflate Accept-Charset ISO-8859-1,utf-8;q=0.7,*;q=0.7 Keep-Alive 115 Connection keep-alive Content-Type application/x-www-form-urlencoded; charset=UTF-8 X-Requested-With XMLHttpRequest Referer https://pqompo2test01.dns.microsoft.com/Incident/List Content-Length 330 Cookie MC1=GUID=111c287d88c64447a63719bb2c858981&HASH=7d28&LV=20114&V=3; A=I&I=AxUFAAAAAACJCAAAMuSpPH1Citx6nZO0iHfvdA!!&CS=116|9n002j21b03; WT_FPC=id=131.107.0.73-1717525904.30146426:lv=1308581948698:ss=1308581948698; MUID=7F438FBFEEE948D88DA06B04F6923159; MSID=Microsoft.CreationDate=04/20/2011 16:45:49&Microsoft.LastVisitDate=06/20/2011 15:59:10&Microsoft.VisitStartDate=06/20/2011 15:59:10&Microsoft.CookieId=4c7552d0-5e75-4e5e-98b9-4ca52421a738&Microsoft.TokenId=ffffffff-ffff-ffff-ffff-ffffffffffff&Microsoft.NumberOfVisits=27&Microsoft.CookieFirstVisit=1&Microsoft.IdentityToken=AA==&Microsoft.MicrosoftId=0668-8044-9161-9043; ANON=A=FA4FB528F204DDFA69239A4FFFFFFFFF&E=b4d&W=4; NAP=V=1.1&E=af3&C=hJtCCJq27admlaiwmdzvTmnAwIEVXv1jFR2I2bJ-gncMGQOJce96RQ&W=4; mcI=Wed, 27 Apr 2011 16:48:43 GMT; omniID=fd752842_58d3_4833_9a0f_d0e1e3bbfef3; WT_NVR_RU=0=msdn:1=:2=; ASP.NET_SessionId=dbcqi222tehjorefcopchuzu; MS0=7fc23d65df4241c89554b502149ccc13; MICROSOFTSESSIONCOOKIE=Microsoft.CookieId=94c8a34f-9184-4e10-84c5-2b9c43c7a962&Microsoft.CreationDate=06/20/2011 15:59:10&Microsoft.LastVisitDate=06/20/2011 15:59:10&Microsoft.NumberOfVisits=1&SessionCookie.Id=04DF98242DBD0730C9388487546F2F37; RPSMCA=FAAaARSsz90pZKmFSg5n0wbtR5MnQAldBwNmAAAEgAAACDNAEUimN1wb2AD%2Bp1PnEJUdd7n5VumQIQerCQYdD5IEd6ZCDEshkiTkvVl5a9eA6%2B9a0Os/1FpoqtvsGYMdWUUc98PUl5ZTo%2BFXAqxiZ9BL5D69OLCPsZEXitrZMulmKXFGQiAD5FqJY8JOOSJ1xptRwdkdrxGF8PuNit/Si87Ft7g4sF9vE878lMSx6TSmQq3nrurnBbdbUvDvwTKLoY0gAikOxJ7GmZoLw4kbzaLR/6/a/XSJFv%2BZ6uHsIwkMn6mndoZKfg3LLjDlCpozrHBlnKtgkn7yZXtd8Or420IXuPMUAF3gfp8VAkhKlVceTXpBv2h4gs6g; RPSMCSA=FAAaARSsz90pZKmFSg5n0wbtR5MnQAldBwNmAAAEgAAACEdSXDQ0SIKI2AC/tM6y7CeHdaKVAab/n/4TLKkF5/01jGkXR0vA07MTvS5vhwgjCPMs4zke%2B0jnB1DqOV2vI4VqQ/%2BOIYh52QkaLREoD5L718AjEJOQdDVRRZiIB51CiYtS0P/kgIkEtfDa5yuTr3w6V2IKhy2%2B6wVrP/UqxsJR%2BZ1QmGxtjv7eQVGdIndrkPx5e9wFqj1qEcf9FNfH0/uajuaTFaNmi/3dQfWuEKxGpoHWNxgoMf8PHLVi2hqltqK47OloCGqQGLPQPx0PSg1K73FTZHhl3%2BuxyNqyWJumKsAUAGuMUzFhTPsQ7JdOSfY2SYyHeaZP; RPSShare=1; MSPAuth=1NNm8kdmWAFrAuL2d8qOShxJKehL!CxEkCQvsgPdNGDqo0XFGsreQZ9GMVjiT1*bHPlGcNVsyfbVO7h!eY32bCNY7Farp2grIyEgAFv7YgJqWZN2Q87*LBZnZ0ASWmhPqe; MSPProf=1ZN*xhGN9GRXSO*HEmrISYo6cowSUbmxtIsYfqtHv!!VzEybb1I33*BdWWJrz54tkO5BzS3eTprAXL1LO9ELLBziO8Sm8WTzkSbV*E6ECcX9N92*AFiJztc4rlwCLQnMBhxlV0qzvlRN4dS1SajyzABZDNBTG*tdyqfnuP6jkSevAhuXYvnEuKZQKAF5fvgr4!oiBQ2KhnuH0$; RequestVerificationToken_Lw=TOS6XUQ+17bDOxh2T75NhhFy2KIJP5BP9MetB7cAa4i68ZEHIEpgE7xwQhzid/YiZCm4GsbW2zsJjlIxkB1hrhVGoU++E1I5BP9X2PyKn0O8tic84cWNz8QRjLDcaAcF4iYEQQ==; prmrsdninc=1

When I run locally on my Win7 machine I simply get the text back that I am expecting.

I was having the same problem trying to return 500 pages containing only text for processing by telerik controls. Of course it worked tickity-boo on my development machine and failed when published up to the proper IIS servers.

This fixed it for me:

http://blog.janjonas.net/2011-04-13/asp_net-prevent-iis_75_overriding-custom-error-page-iis-default-error-page

Summary: Type putting a

Response.TrySkipIisCustomErrors = true;

line in your action