asp.net C#中的按钮单击事件出错

<!-- 错误示例 -->
<asp:Button ID="btnSubmit" runat="server" Text="提交" />

<!-- 正确声明 -->
<asp:Button ID="btnSubmit" runat="server" Text="提交" OnClick="btnSubmit_Click" />

// 后台方法
protected void btnSubmit_Click(object sender, EventArgs e)
{
    // 处理逻辑
}

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        // 初始化代码
    }
}

// 错误示例
async void btnSubmit_Click(object sender, EventArgs e)
{
    await Task.Run(() => {
        lblMessage.Text = "完成"; // 线程冲突
    });
}

async void btnSubmit_Click(object sender, EventArgs e)
{
    string result = await Task.Run(() => DoWork());
    lblMessage.Text = result; // 回到UI线程
}

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        btnSubmit.Click += btnSubmit_Click; // 仅绑定一次
    }
}

<system.web>
    <trace enabled="true" pageOutput="true"/>
</system.web>

protected override void OnInit(EventArgs e)
{
    var btn = new Button { ID = "btnDynamic" };
    btn.Click += btnDynamic_Click;
    form1.Controls.Add(btn);
    base.OnInit(e);
}

<asp:ScriptManager runat="server"/>
<asp:UpdatePanel runat="server">
    <ContentTemplate>
        <asp:Button runat="server" OnClick="btnAjax_Click"/>
    </ContentTemplate>
</asp:UpdatePanel>

<asp:Button OnClientClick="return confirm('确定执行？')" ... />