Getting text/html Response instead of application/json on user machine in case of Exception

Question

I am experiencing strange issue with JSON response.

MVC Application A hosted on Server A. when user browse the URL which internally calls MVC action for fetching data in UI using JQuery Ajax.

MVC action :

    Try
       Return Json(mRetResponse, JsonRequestBehavior.AllowGet)
    Catch ex As Exception
                    HttpContext.Response.StatusCode = System.Net.HttpStatusCode.InternalServerError
                    Dim mErrorMessage As String = ex.Message.Replace("Error -", "")

                    <<ObjErrorResponse is created here by assigning error message.>>

                    Return Json(ObjErrorResponse, JsonRequestBehavior.AllowGet)
                End Try

JQUERY Call

CommonJS.ShowProgress();
                CommonJS.ajaxPost(_Controller + "/Delete"
                    , 'json'
                    , { // dataParam // }
                    , function (msg) {
                        CommonJS.HideProgress();
                        var responseObj = msg;
                        if (responseObj.Success) {
                            if ((responseObj.Data) && typeof responseObj.Data === 'string') {
                                alert(responseObj.Data);
                            }
                            //Processing goes here 
                        }
                        else {
                            CommonJS.ShowErrors(responseObj);
                        }                        
                    }
                    , function (jqxhr, textStatus, error) {
                        CommonJS.HandleErrors(jqxhr);
                    }
                    , true
                );

When we browser MVC application URL on user machine (other than server machine) we are getting below behaviour

In case of Success; we are getting JSON correctly both on server machine and User machine.
In case of Exception raised we send JSON error Response which eventually shown some error message to user. - it working fine when we physically browse that MVC URL on server machine. However we get issue only on user machine it shows text/html as response in user browser. rather than application/json.

Couple of More Information from User machine.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1"/>
<title>500 - Internal server error.</title>
<style type="text/css">
<!--
body{margin:0;font-size:.7em;font-family:Verdana, Arial, Helvetica, sans-serif;background:#EEEEEE;}
fieldset{padding:0 15px 10px 15px;} 
h1{font-size:2.4em;margin:0;color:#FFF;}
h2{font-size:1.7em;margin:0;color:#CC0000;} 
h3{font-size:1.2em;margin:10px 0 0 0;color:#000000;} 
#header{width:96%;margin:0 0 0 0;padding:6px 2% 6px 2%;font-family:"trebuchet MS", Verdana, sans-serif;color:#FFF;
background-color:#555555;}
#content{margin:0 0 0 2%;position:relative;}
.content-container{background:#FFF;width:96%;margin-top:8px;padding:10px;position:relative;}
-->
</style>
</head>
<body>
<div id="header"><h1>Server Error</h1></div>
<div id="content">
 <div class="content-container"><fieldset>
  <h2>500 - Internal server error.</h2>
  <h3>There is a problem with the resource you are looking for, and it cannot be displayed.</h3>
 </fieldset></div>
</div>
</body>
</html>

Expected Response:

{"Success":false,"Data":null,"Errors":[{"ErrorMessage":"Unable to peform Delete operation."}],"CustomData":{}}

Are you sure it's the same error? *eventually shown "some" error* implies a different error. — freedomn-m, Dec 08 '21 at 14:14
Host probably expects an html error page when an exception occurs so it does not use the json serializer. You probably need to use a custom exception handler middleware. — Berkays, Dec 08 '21 at 14:18
@CaiusJard More information provided. Let me know if you need any thing more. — Dinesh Prajapati, Dec 09 '21 at 06:32
@Berkays Could you please elaborate more. how hosts decide that it expects HTML error page we did not have that kind of configuration. have a look on more information which have been attached. — Dinesh Prajapati, Dec 09 '21 at 06:35
And when you debug it, does the catch handler actually run to the end and call `Json(...)` or does an exception occur inside the Catch.. for example this Catch would fail: `Try .. Catch` `Dim o as Object = Nothing` `Dim s = o.ToString()` `Return Json(s)` `End Try` — Caius Jard, Dec 09 '21 at 07:16

score 0 · Accepted Answer · answered Dec 09 '21 at 15:51

0

In addition to setting the status code, you'll need to set the TrySkipCustomIisErrors property on the response. Otherwise, IIS will see a 500 response and return its custom "internal server error" page instead of your own JSON response.

answered Dec 09 '21 at 15:51

Richard Deeming

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Though I did not found the answer what cause this behavior change in IIS. Because earlier it was working without any of this. Found Couple of more links which could be useful to others. https://serverfault.com/questions/123729/iis-is-overriding-my-response-content-if-i-manually-set-the-response-statuscode https://stackoverflow.com/questions/2640526/detailed-500-error-message-asp-iis-7-5 https://learn.microsoft.com/en-us/iis/configuration/system.webServer/httpErrors/ – Dinesh Prajapati Dec 14 '21 at 11:43

Getting text/html Response instead of application/json on user machine in case of Exception

1 Answers1