jQuery ajax json webservice error

If someone could point out what's wrong here I would certainly appreciate it. I can set a breakpoint in the webmethod and it gets hit, but it always errors out.

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="AJAX_Test._Default" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
    <head runat="server">
        <title>AJAX Test</title>
        <script src="Scripts/jquery-1.7.min.js" type="text/javascript"></script>
        <form id="form1" runat="server">
            <button id="theButton">Click Here</button>
        <script type="text/javascript">
            $(function () {
                $("#theButton").on("click", function () {
                        type: "POST",
                        url: "AjaxWebService.asmx/HelloWorld",
                        contentType: "application/json; charset=utf-8",
                        dataType: "json",
                        data: "{}",
                        success: AjaxSucceeded,
                        error: AjaxFailed

            function AjaxSucceeded(data, status) {

            function AjaxFailed(jqXHR, textStatus, errorThrown) {

using System;
using System.Collections.Generic;
using System.Web;
using System.Web.Services;

namespace AJAX_Test
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]

    public class AjaxWebService : System.Web.Services.WebService
        public string HelloWorld()
            return "Hello World";


Here is your problem:

Add this attribute to your service:


and add this to your method:

[ScriptMethod(ResponseFormat = ResponseFormat.Json)]

When you connect to a service from javascript it must have those attributes.

Need Your Help

Can not get the distinct NULL from database

c# sql sqldatareader

I want to extracing a column from a database and save it into a list. Now it works but NULL value.