为什么我得到这个System.NullReferenceException？

Question

我收到了一个奇怪的错误.我有以下前端代码:

<%@ Page Title="" Language="C#" MasterPageFile="~/nokernok/MasterPages/nokernok.Master" AutoEventWireup="true" CodeBehind="articleList.aspx.cs" Inherits="development.nokernok.articleList" %>
<%@ Register TagPrefix="EPiServer" Namespace="EPiServer.WebControls" Assembly="EPiServer" %>

<asp:Content ID="Content2" ContentPlaceHolderID="LeftContentPlaceHolder" runat="server">    
    <asp:Label ID="lblTest" runat="server" />    
</asp:Content>

我有以下后端代码:

using System;
using System.Web;
using EPiServer;
using EPiServer.Core;
using development.NaafLibrary;

namespace development.nokernok
{
    public partial class articleList : TemplatePage
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            lblTest.Text = "TEEEEEEEEEEEST";    
        }
    }
}

设计师档案:

namespace development.nokernok {
    public partial class articleList {        
       protected global::System.Web.UI.WebControls.Label lblTest;
    }
}

我得到这个错误消息:

Object reference not set to an instance of an object.
Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

[NullReferenceException: Object reference not set to an instance of an object.]
development.nokernok.articleList.Page_Load(Object sender, EventArgs e) in C:\Inetpub\wwwroot\naaf\nokernok\articleList.aspx.cs:17
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
System.EventHandler.Invoke(Object sender, EventArgs e) +0
System.Web.UI.Control.OnLoad(EventArgs e) +99
System.Web.UI.Control.LoadRecursive() +50
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627

我有其他模板可以正常工作.我只是不明白为什么我在这里得到这个错误.

更新1:

我刚刚添加了一些代码.

Answer 1

检查相关的.aspx.designer.cs是否有

protected global::System.Web.UI.WebControls.Label lblTest;