Getting Failed to load Resource: the sever responded with a status 500 ()

Question

Using a simple MVC5 CRUD web app using razor and jquery to popup div window to add and update records connected to SQLserver via ado.net EF6. I have one view and controller working fine. The issue happens when I copied and updated a new view and controller. Please see the code of the view and controller and thank you for any assistance on this issue.

View:Index.cshtml

@{
    ViewBag.Title = "Dept List";
}

<h2>Department</h2>

<a class="btn btn-success" style="margin-bottom:10px" onclick="PopupForm('@Url.Action("AddOrEdit","Dept")')"><i class="fa fa-plus"></i> Add New</a>
<table id="deptTable" class="table table-striped table-bordered" style="width:100%">
    <thead>
        <tr>
            <th>Name</th>
            <th>Phone</th>
            <th>Fax</th>
            <th>Loc</th>
            <th>Address</th>
            <th>Stop</th>
            <th>URL</th>
            <th></th>
        </tr>
    </thead>
</table>

<link href="https://cdn.datatables.net/1.10.15/css/dataTables.bootstrap.min.css" rel="stylesheet" />
<link href="https://maxcdn.bootstrapcdn.com/font-awesome/4.7.0/css/font-awesome.min.css" rel="stylesheet" />

@section scripts{
    <script src="//cdn.datatables.net/1.10.15/js/jquery.dataTables.min.js"></script>
    <script src="https://cdn.datatables.net/1.10.15/js/dataTables.bootstrap.min.js"></script>

    <script>
        var Popup, dataTable;
        $(document).ready(function () {
            dataTable =  $("#deptTable").DataTable({
                "ajax": {
                    "url": "/Dept/GetData",
                    "type": "GET",
                    "datatype": "json"
                },
                "columns": [
                    { "data": "Name" },
                    { "data": "Phone" },
                    { "data": "Fax" },
                    { "data": "Location" },
                    { "data": "Address" },
                    { "data": "MailStop" },
                    { "data": "URL" },
                    {"data":"DeptID" , "render" : function (data) {
                        return "&nbsp;<a class='btn btn-default btn-sm' onclick=PopupForm('@Url.Action("AddOrEdit","Dept")/" + data + "')><i class='fa fa-pencil'></i> Edit&nbsp;&nbsp;&nbsp;&nbsp;</a><a class='btn btn-danger btn-sm' style='margin-left:5px' onclick=Delete(" + data +")><i class='fa fa-trash'></i> Delete</a>";
                    },
                        "orderable": false,
                        "searchable":false,
                        "width":"150px"
                    }

                ],
                "language": {

                    "emptyTable" : "No data found, Please click on <b>Add New</b> Button"
                }
            });
        });

        function PopupForm(url) {
            var formDiv = $('<div/>');
            $.get(url)
            .done(function (response) {
                formDiv.html(response);

                Popup = formDiv.dialog({
                    autoOpen: true,
                    resizable: false,
                    title: 'Add New Department Details',
                    height: 400,
                    width: 700,
                    close: function () {
                        Popup.dialog('destroy').remove();
                    }

                });
            });
        }

PopUp Div
AddOrEdit.cshmtl
@model Deparment.Models.tblDept
@{
    Layout = null;
}

@using (Html.BeginForm("AddOrEdit", "Dept", FormMethod.Post, new { onsubmit = "return SubmitForm(this)" }))
{
    @Html.HiddenFor(model => model.DeptID)
<div class="form-group">
    @Html.LabelFor(model => model.Dept, new { @class = "control-label" })
    @Html.EditorFor(model => model.Dept, new { htmlAttributes = new { @class = "form-control" } })
    @Html.ValidationMessageFor(model => model.DeptName)
</div>
    <div class="form-group">
        @Html.LabelFor(model => model.Phone, new { @class = "control-label" })
        @Html.EditorFor(model => model.Phone, new { htmlAttributes = new { @class = "form-control" } })   
    </div>
    <div class="form-group">
        @Html.LabelFor(model => model.Fax, new { @class = "control-label" })
        @Html.EditorFor(model => model.Fax, new { htmlAttributes = new { @class = "form-control" } })
    </div>
    <div class="form-group">
        @Html.LabelFor(model => model.Location, new { @class = "control-label" })
        @Html.EditorFor(model => model.Location, new { htmlAttributes = new { @class = "form-control" } })
    </div>
    <div class="form-group">
        @Html.LabelFor(model => model.Address, new { @class = "control-label" })
        @Html.EditorFor(model => model.Address, new { htmlAttributes = new { @class = "form-control" } })
    </div>
    <div class="form-group">
        @Html.LabelFor(model => model.MailStop, new { @class = "control-label" })
        @Html.EditorFor(model => model.MailStop, new { htmlAttributes = new { @class = "form-control" } })
    </div>
    <div class="form-group">
        @Html.LabelFor(model => model.URL, new { @class = "control-label" })
        @Html.EditorFor(model => model.URl, new { htmlAttributes = new { @class = "form-control" } })
    </div>
    <div class="form-group">
        <input type="submit" value="Submit" class="btn btn-primary" />
        <input type="reset" value="Reset" class="btn" />
    </div>
}

Controller:

namespace Department.Controllers
{
    public class DeptController : Controller
    {
        //
        // GET: /Dept/
        public ActionResult Index()
        {
            return View();
        }

        public ActionResult GetData()
        {
            using (DBModel db = new DBModel())
            {
                List<tblDept> deptList = db.tblDepts.ToList<tblDept>();
                return Json(new { data = deptList }, JsonRequestBehavior.AllowGet);
            }
        }


        [HttpGet]
        public ActionResult AddOrEdit(int id = 0)
        {
            if (id == 0)
                return View(new tblDept());
            else
            {
                using (DBModel db = new DBModel())
                {
                    return View(db.tblDepts.Where(x => x.DeptID==id).FirstOrDefault<tblDept>());
                }
            }
        }

        [HttpPost]
        public ActionResult AddOrEdit(tblDept dept)
        {
            using (DBModel db = new DBModel())
            {
                if (dept.DeptID == 0)
                {
                    db.tblDepts.Add(dept);
                    db.SaveChanges();
                    return Json(new { success = true, message = "Saved Successfully" }, JsonRequestBehavior.AllowGet);
                }
                else {
                    db.Entry(dept).State = EntityState.Modified;
                    db.SaveChanges();
                    return Json(new { success = true, message = "Updated Successfully" }, JsonRequestBehavior.AllowGet);
                }
            }


        }

        [HttpPost]
        public ActionResult Delete(int id)
        {
            using (DBModel db = new DBModel())
            {
                tblDept dept = db.tblDepts.Where(x => x.DeptID == id).FirstOrDefault<tblDept>();
                db.tblDepts.Remove(dept);
                db.SaveChanges();
                return Json(new { success = true, message = "Deleted Successfully" }, JsonRequestBehavior.AllowGet);
            }
        }
    }
}