500 internal server error on populating dropdownlist through AJAX call to webservice.

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My webservice is not getting called. I am getting 500 internal server error. what should i do?

This is the HTML coding:

HTML

$(window).load(function () {
<pre>              $.ajax({
                        type: "GET",
                        data: {},
                        url:  "services/VisiTracWS.asmx/GetLocation",
                        success: function (response) {
                            alert("1");
                            var strSection = '<option value="0">Select Location</option>';
                            if (response.d.length > 0) {
                                for (i = 0; i < response.d.length; i++) {
                                    strSection = strSection + '<option value="' + response.d[i].LocationID + '">' + response.d[i].LocationName + '</option>';
                                }
                            }
                            $('#ddlLocations').html(strSection);
                        },
                        error: function (response) {
                            alert(response.status + " " + response.statusText);
                        }
                    });
                });

This is the webservice:

C#

<pre>[WebMethod]
        public static List<Location> GetLocation()
        {
            List<Location> lst = new List<Location>();
            try
            {
                visitrac.Location lc = new visitrac.Location();
                DataTable DT = lc.GetDropdown();

                lst = (from DataRow dr in DT.Rows
                       select new Location()
                       {
                           LocationID = Convert.ToInt32(dr["LocationID"]),
                           LocationName = Convert.ToString(dr["LocationName"]),
                       }).ToList();
            }
            catch (Exception ex)
            {
                // clsException.WriteLog("", "GetLocation", ex.Message);
            }
            return lst;
        }

What I have tried:

I have tried making the method static. changing POST to GET

Posted 7-Aug-17 20:59pm

prapti.n3

Updated 7-Aug-17 23:42pm

v2

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Comments

Richard MacCutchan 8-Aug-17 3:40am

What you should do is look at the server logs to find out why it gave the 500 error.

prapti.n3 8-Aug-17 3:59am

where do I find server logs in Mozilla firefox??

Richard MacCutchan 8-Aug-17 4:22am

Look on the server.

Karthik_Mahalingam 8-Aug-17 4:03am

is the url accessible from browser address bar ?

prapti.n3 8-Aug-17 4:40am

yes.. i can access the web service

F-ES Sitecore 8-Aug-17 4:14am

https://forums.asp.net/t/1982579.aspx?Using+the+browser+s+dev+tools+to+diagnose+ajax+problems+and+other+things+

Dave Kreskowiak 8-Aug-17 8:28am

500 errors mean that the server code crashed or could not run for some reason.

Typically, this is something you diagnose using the debugger. Put a breakpoint on the first line of the GetLocation method and run the code. Go through your browser and do what you did before to cause the crash. When the code on the server-side runs, it'll hit the breakpoint and you can use the debugger to step through the code and examine variable contents to help you figure out why it crashed.

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Karthik_Mahalingam · Answer 1 · 2017-08-07T23:42:00

try like this

Web Service c#

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

namespace WebApplication135.services
{
    
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)] 
    [System.Web.Script.Services.ScriptService]
    public class VisiTracWS : System.Web.Services.WebService
    {

        [WebMethod]
        public   Location[] GetLocation()
        {
            List<Location> lst = new List<Location>();
            lst.Add(new Location() { LocationID = 1, LocationName = "India" });
            lst.Add(new Location() { LocationID = 2, LocationName = "Australia" });
            lst.Add(new Location() { LocationID = 3, LocationName = "China" });
            return lst.ToArray();
        }
    }

    public class Location {
        public int LocationID { get; set; }
        public string LocationName { get; set; }

    }
}