JQuery Ajax Post results in 500 Internal Server Error

Question

I am trying to perform this AJAX post but for some reason I am getting a server 500 error. I can see it hit break points in the controller. So the problem seems to be on the callback. Anyone?

$.ajax({
    type: "POST",
    url: "InlineNotes/Note.ashx?id=" + noteid,
    data: "{}",
    dataType: "json",

    success: function(data) {
        alert(data[1]);
    },
    error: function(data){
        alert("fail");
    }
});

This is the string that should be returned:

{status:'200', text: 'Something'}

Answer 1

I suspect that the server method is throwing an exception after it passes your breakpoint. Use Firefox/Firebug or the IE8 developer tools to look at the actual response you are getting from the server. If there has been an exception you'll get the YSOD html, which should help you figure out where to look.

One more thing -- your data property should be {} not "{}", the former is an empty object while the latter is a string that is invalid as a query parameter. Better yet, just leave it out if you aren't passing any data.

Answer 2

in case if someone using the codeigniter framework, the problem may be caused by the csrf protection config enabled.

Answer 3

This is Ajax Request Simple Code To Fetch Data Through Ajax Request

$.ajax({
    type: "POST",
    url: "InlineNotes/Note.ashx",
    data: '{"id":"' + noteid+'"}',
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: function(data) {
        alert(data.d);
    },
    error: function(data){
        alert("fail");
    }
});

Answer 4

I just had this problem myself, even though i couldn't find the reason for it in my case, when changing from POST to GET, the problem 500 error disappeared!

 type:'POST'

Answer 5

I experienced a similar compound error, which required two solutions. In my case the technology stack was MVC/ ASP.NET / IIS/ JQuery. The server side was failing with a 500 error, and this was occurring before the request was handled by the controller making the debug on the server side difficult.

The following client side debug enabled me to determine the server error

In the $.ajax error call back, display the error detail to the console

  error: (error) => {
                     console.log(JSON.stringify(error));
   }

This at least, enabled me to view the initial server error

“The JSON request was too large to be serialized”

This was resolved in the client web.config

<appSettings>
    <add key="aspnet:MaxJsonDeserializerMembers" value="150000" />

However, the request still failed. But this time with a different error that I was now able to debug on the server side

“Request Entity too large”

This was resolved by adding the following to the service web.config

<configuration>
…
 <system.serviceModel>
    <bindings>
      <basicHttpBinding>
        <binding maxBufferSize="2147483647" maxReceivedMessageSize="2147483647" maxBufferPoolSize="524288">
          <readerQuotas maxDepth="32" maxStringContentLength="2147483647"
            maxArrayLength="2147483647" maxBytesPerRead="2147483647" maxNameTableCharCount="2147483647"  />
        </binding>
      </basicHttpBinding>
    </bindings>

The configuration values may require further tuning, but at least it resolved the server errors caused by the ajax post.

Answer 6

You can look up HTTP status codes here (or here), this error is telling you:

"The server encountered an unexpected condition which prevented it from fulfilling the request."

You need to debug your server.

Answer 7

I run into the same thing today. As suggested before get Firebug for Firefox, Enable Console and preview POST response. That helped me to find out how stupid the problem was. My action was expecting value of a type int and I was posting string. (ASP.NET MVC2)

Answer 8

There should be an event logged in the EventVwr (Warning from asp.net), which could provide you more details on where the error could be.

Answer 9

A 500 from ASP.NET probably means an unhandled exception was thrown at some point when serving the request.

I suggest you attach a debugger to the web server process (assuming you have access).

One strange thing: You make a POST request to the server, but you do not pass any data (everything is in the query string). Perhaps it should be a GET request instead?

You should also double check that the URL is correct.

Answer 10

I just face this problem today. with this kind of error, you won't get any responses from server, therefore, it's very hard to locate the problem.

But I can tell you "500 internal server error" is error with server not client, you got an error in server side script. Comment out the code closure by closure and try to run it again, you'll soon find out you miss a character somewhere.

Answer 11

You can also get that error in VB if the function you're calling starts with Public Shared Function rather than Public Function in the webservice. (As might happen if you move or copy the function out of a class). Just another thing to watch for.

Answer 12

Can you post the signature of your method that is supposed to accept this post?

Additionally I get the same error message, possibly for a different reason. My YSOD talked about the dictionary not containing a value for the non-nullable value. The way I got the YSOD information was to put a breakpoint in the $.ajax function that handled an error return as follows:

<script type="text/javascript" language="javascript">
function SubmitAjax(url, message, successFunc, errorFunc) {
    $.ajax({
        type:'POST',
        url:url,
        data:message,
        contentType: 'application/json; charset=utf-8',
        dataType: 'json',
        success:successFunc,
        error:errorFunc
        });

};

Then my errorFunc javascript is like this:

function(request, textStatus, errorThrown) {
        $("#install").text("Error doing auto-installer search, proceed with ticket submission\n"
        +request.statusText); }

Using IE I went to view menu -> script debugger -> break at next statement. Then went to trigger the code that would launch my post. This usually took me somewhere deep inside jQuery's library instead of where I wanted, because the select drop down opening triggered jQuery. So I hit StepOver, then the actual next line also would break, which was where I wanted to be. Then VS goes into client side(dynamic) mode for that page, and I put in a break on the $("#install") line so I could see (using mouse over debugging) what was in request, textStatus, errorThrown. request. In request.ResponseText there was an html message where I saw:

<title>The parameters dictionary contains a null entry for parameter 'appId' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ContentResult CheckForInstaller(Int32)' in 'HLIT_TicketingMVC.Controllers.TicketController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter.<br>Parameter name: parameters</title>

so check all that, and post your controller method signature in case that's part of the issue

Answer 13

In my case it was simple issue, but hard to find. Page directive had wrong Inherits attributes. It just need to include the top level and it worked.

Wrong code

<%@ Page Language="C#" CodeBehind="BusLogic.aspx.cs" Inherits="BusLogic"%>

Correct code

<%@ Page Language="C#" CodeBehind="BusLogic.aspx.cs" Inherits="Web.BusLogic" %>

Answer 14

I was able to find the solution using the Chrome debugger (I don't have Firebug or other third-party tools installed)

• Go to developer tab (CTRL+MAJ+I)
• Network > click on the request which failed, in red > Preview

It showed me that I had a problem on the server, when I was returning a value which was self-referencing.

Answer 15

I found myself having this error to. I had .htaccess redirect configured in a directory. Well it reroutes ajax calls to ofcourse ($.post(../ajax.php)), so it couldn't find the actual file (resulting in 500 error).

I 'fixed' it by placing the ajax.php in a directory (So .htaccess didn't affect).

Answer 16

I found this occurred in chrome when I did two ajax queries in the jquery 'on load' handler,

i.e. like $(function() { $.ajax() ... $.ajax() ... });

I avoided it using:

setTimeout(function_to_do_2nd_ajax_request, 1);

it's presumably a chrome and/or jquery bug

Answer 17

When using the CodeIgniter framework with CSRF protection enabled, load the following script in every page where an ajax POST may happen:

$(function(){
    $.ajaxSetup({
        data: {
            <?php echo $this->config->item('csrf_token_name'); ?>: $.cookie('<?php echo $this->config->item('csrf_cookie_name'); ?>')
        }
    });
});

Requires: jQuery and jQuery.cookie plugin

Sources: https://stackoverflow.com/a/7154317/2539869 and http://jerel.co/blog/2012/03/a-simple-solution-to-codeigniter-csrf-protection-and-ajax

Answer 18

I had this problem because the page I called ajax post from had EnableViewState="false" and EnableViewStateMac="false" but not the page called.

When I put this on both pages everything started to work. I suspected this when I saw MAC address exception.

Answer 19

The JSON data you are passing to the server should have same name as you forming in client side. Ex:

var obj = {  Id: $('#CompanyId').val(),
             Name: $("#CompanyName").val()
            };

$.Ajax(data: obj,
url: "home/InsertCompany".....

If the name is different, ex:

[HttpPost]
public ActionResult InsertCompany(Int32 Id, string WrongName)
{
}

You will get this error.

If you are not passing the data, remove the data attribute from AJAX request.

Answer 20

I had this issue, and found out that the server side C# method should be static.

Client Side:

$.ajax({
            type: "POST",
            url: "Default.aspx/ListItem_Selected",
            data: "{}",
            dataType: "json",
            contentType: "application/json; charset=utf-8",
            success: ListItemElectionSuccess,
            error: ListItemElectionError
        });

        function ListItemElectionSuccess(data) {
            alert([data.d]);
        }
        function ListItemElectionError(data) {

        }

Server Side:

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    [WebMethod]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
    public static String ListItem_Selected()
    {
        return "server responce";
    }
}

Answer 21

As mentioned I think your return string data is very long. so the JSON format has been corrupted.

There's other way for this problem. You should change the max size for JSON data in this way :

Open the Web.Config file and paste these lines into the configuration section

<system.web.extensions>
  <scripting>
    <webServices>
      <jsonSerialization maxJsonLength="50000000"/>
    </webServices>
  </scripting>
</system.web.extensions>

Answer 22

Use a Try Catch block on your server side and in the catch block pass back the exception error to the client. This should give you a helpful error message.

Answer 23

I also faced the same problem. Here are two ways by which I have solved it- 1. If you're using some framework, make sure you are sending a CSRF token with the ajax call as well Here is how the syntax will look like for laravel -

<meta name="_token" content="{{ csrf_token() }}">

In your js file make sure to call this before sending the ajax call

$.ajaxSetup({
            headers: {
                'X_CSRF-TOKEN' : $('meta[name="_token"]').attr('content')
            }
        });

2. Another way to solve it would be to change method from post to get

Answer 24

For me, the error was in php file to which i was sending request. Error was in database connectivity. After fixing the php code, error resolved.

Answer 25

Your code contains dataType: json.

In this case jQuery evaluates the response as JSON and returns a JavaScript object. The JSON data is parsed in a strict manner. Any malformed JSON is rejected and a parse error is thrown. An empty response is also rejected.

The server should return a response of null or {} instead.

Answer 26

Your return string data can be very long.

<system.web>        
   <compilation debug="true" targetFramework="4.0" />
   <httpRuntime maxRequestLength="2147483647" />
</system.web>

For example:

• 1 Char = 1 Byte
• 5 Char = 5 Byte
• "Hakki" = 5 Byte

Answer 27

I have had similar issues with AJAX code that sporadically returns the "500 internal server error". I resolved the problem by increasing the "fastCGI" RequestTimeout and ActivityTimeout values.

Answer 28

I'm late on this, but I was having this issue and what I've learned was that it was an error on my PHP code (in my case the syntax of a select to the db). Usually this error 500 is something to do using syntax - in my experience. In other word: "peopleware" issue! :D

Answer 29

As an addition to the "malformed JSON" answer, if the query you are running returns an object or anything that prevents the data to be serialised, you will get this error. You should always be sure you have JSON and only JSON at the end of your action method or whatever it is you are getting the data from.

Answer 30

Usually your property is not completely right or something wrong with your server processing.

Answer 31

try this headers: { 'X-Requested-With': 'XMLHttpRequest' }, in ajax, set type above the url

Answer 32

In my case the error was related to the way entity framework works. I had a one to many relationship between two tables in my database and when I was bringing data from the table which has the foreign key using ajax post it was also fetching the related foreign key table data because lazyloading was enabled by default. because of that , Json return got confused about the data format and was throwing this error. So I had to use _wfocEntities.Configuration.LazyLoadingEnabled = false; this line before my linq query and it solved my issue.

Answer 33

In my case, i was trying server side processing for datatables. And my action method returns thousands of user record as JSON. The problem was JSON max length. This solved my problem.

return new JsonResult()
        {
            ContentEncoding = Encoding.Default,
            ContentType = "application/json",
            Data = returnData,
            JsonRequestBehavior = JsonRequestBehavior.AllowGet,
            MaxJsonLength = int.MaxValue //this is what,I needed.
        };