c# - MVC 4 楽観的同時実行例外

Question

この問題に直面して(ブートストラップ モーダル ウィンドウを使用して編集できるようにしたかったのですが、MVC4 とエンティティ フレームワークを使用しています)、変更を保存しようとすると、モーダル ウィンドウを使用しているため、次のエラー メッセージが表示されます。

Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries.

ここに私の行動があります：

[HttpGet]
        public ActionResult EditPerson(long id)
        {
            var person = db.Persons.Single(p => p.Id_Person == id);

            ViewBag.Id_ProductPackageCategory = new SelectList(db.ProductPackageCategories, "Id_ProductPackageCategory", "Name", person.Id_ProductPackageCategory);

            return PartialView("_EditPerson", person);
        }

        [HttpPost]
        public ActionResult EditPerson(Person person)
        {
            ViewBag.Id_ProductPackageCategory = new SelectList(db.ProductPackageCategories, "Id_ProductPackageCategory", "Name", person.Id_ProductPackageCategory);

            if (ModelState.IsValid)
            {
                ModelStateDictionary errorDictionary = Validator.isValid(person);

                if (errorDictionary.Count > 0)
                {
                    ModelState.Merge(errorDictionary);
                    return View(person);
                }

                db.Persons.Attach(person);
                db.ObjectStateManager.ChangeObjectState(person, EntityState.Modified);
                db.SaveChanges();
                return View("Index");
            }

            return View(person);
        }

私の部分的な見解：

@model BuSIMaterial.Models.Person

<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button>
    <h3 id="myModalLabel">Edit</h3>
</div>
<div>

@using (Ajax.BeginForm("EditPerson", "Person", FormMethod.Post,
                    new AjaxOptions
                    {
                        InsertionMode = InsertionMode.Replace,
                        HttpMethod = "POST",
                        UpdateTargetId = "table"
                    }))
{

    @Html.ValidationSummary()
    @Html.AntiForgeryToken()

    <div class="modal-body">
       <div class="editor-label">
            First name :
        </div>
        <div class="editor-field">
            @Html.TextBoxFor(model => model.FirstName, new { maxlength = 50 })
            @Html.ValidationMessageFor(model => model.FirstName)
        </div>
        <div class="editor-label">
            Last name :
        </div>
        <div class="editor-field">
            @Html.TextBoxFor(model => model.LastName, new { maxlength = 50 })
            @Html.ValidationMessageFor(model => model.LastName)
        </div>
        <div class="editor-label">
            National number :
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.NumNat, new { maxlength = 11 })
            @Html.ValidationMessageFor(model => model.NumNat)
        </div>
        <div class="editor-label">
            Start date :
        </div>
        <div class="editor-field">
            @Html.TextBoxFor(model => model.StartDate, new { @class = "datepicker", @Value = Model.StartDate.ToString("yyyy/MM/dd") })
            @Html.ValidationMessageFor(model => model.StartDate)
        </div>
        <div class="editor-label">
            End date :
        </div>
        <div class="editor-field">
            @if (Model.EndDate.HasValue)
            {
                @Html.TextBoxFor(model => model.EndDate, new { @class = "datepicker", @Value = Model.EndDate.Value.ToString("yyyy/MM/dd") })
                @Html.ValidationMessageFor(model => model.EndDate)
            }
            else
            {
                @Html.TextBoxFor(model => model.EndDate, new { @class = "datepicker" })
                @Html.ValidationMessageFor(model => model.EndDate)
            }
        </div>
        <div class="editor-label">
            Distance House - Work (km) :
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.HouseToWorkKilometers)
            @Html.ValidationMessageFor(model => model.HouseToWorkKilometers)
        </div>
        <div class="editor-label">
            Category :
        </div>
        <div class="editor-field">
            @Html.DropDownList("Id_ProductPackageCategory", "Choose one ...")
            @Html.ValidationMessageFor(model => model.Id_ProductPackageCategory) <a href="../ProductPackageCategory/Create">
                Add a new category?</a>
        </div>
        <div class="editor-label">
            Upgrade? :
        </div>
        <div class="editor-field">
            @Html.EditorFor(model => model.Upgrade)
            @Html.ValidationMessageFor(model => model.Upgrade)
        </div>
    </div>
    <div class="modal-footer">
        <button class="btn btn-inverse" type="submit">Save</button>
    </div>
}

何が起こっているかについて何か考えはありますか？