Event handling is not working for all controls in my ASP.NET web application

Any button Onclick event is not working on my project. I inserted one more button called button1 for testing if it works but found that it is not working by changing the text of a label. Unfortunately, It is not working at all. Only page load event-driven is working.

The problem is not solved with other controls. For example, after the user clicks on an update button, a function will be called that checks the value in the textbox and make some calculation. After debugging, I found that the program cannot read any values from the textbox.

Note: I am using packages like bootstrap, Ajax as they are already built-in in the asp.net web forms web applications. I have also tried to exclude them from the project as mentioned in some references, however, nothing changed.

<%@ Page Title="" Language="C#" MasterPageFile="~/Site.Master" AutoEventWireup="true" CodeBehind="ShoppingCart.aspx.cs" Inherits="Celebreno.ShoppingCart" %>

<asp:Content ID="Content1" ContentPlaceHolderID="MainContent" runat="server">



    <div id="ShoppingCartTitle" runat="server" class="ContentHead">
        <h1>Shopping Cart</h1>
    </div>

    <%--Start of the GridView to display the items in the cart--%>
    <asp:GridView ID="CartList" runat="server" AutoGenerateColumns="False" ShowFooter="True" GridLines="Vertical" CellPadding="4"
        ItemType="Celebreno.Models.ItemsInCart" SelectMethod="GetShoppingCartItems"
        CssClass="table table-striped table-bordered">
        <Columns>

            <%--problem solved : change "ID" to "ServicePack.ID"--%>
            <asp:BoundField DataField="ServicePack.ID" HeaderText="Service Package ID" SortExpression="ID" />
            <asp:BoundField DataField="ServicePack.Provider" HeaderText="Provider" />
            <asp:BoundField DataField="ServicePack.UnitPrice" HeaderText="Price (each)" DataFormatString="{0:c}" />
            <asp:TemplateField HeaderText="Quantity">
                <ItemTemplate>
                    <asp:TextBox ID="PurchaseQuantity" Width="40" runat="server" Text="<%#: Item.Quantity %>" ></asp:TextBox>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Item Total">
                <ItemTemplate>
                    <%#: String.Format("{0:c}", ((Convert.ToDouble(Item.Quantity)) *  Convert.ToDouble(Item.ServicePack.UnitPrice)))%>
                </ItemTemplate>
            </asp:TemplateField>
            <asp:TemplateField HeaderText="Remove Item">
                <ItemTemplate>

                    <%--checkbox for removing the item--%>
                    <asp:CheckBox ID="Remove" runat="server"></asp:CheckBox>

                </ItemTemplate>
            </asp:TemplateField>
        </Columns>
    </asp:GridView>
    <%--End of the GridView--%>

    <div>
        <p></p>
        
            <asp:Label ID="LblTotalText" runat="server" Text="Order Total: "></asp:Label>
            <asp:Label ID="LblTotal" runat="server" EnableViewState="false"></asp:Label>
        
    </div>
    <br />



    <table>
        <tr>
            <td>
                <asp:Button ID="UpdateBtn" runat="server" Text="Update" OnClick="UpdateBtn_Click" CausesValidation="False" UseSubmitBehavior="false" />
               
            </td>
            <td>

                <%--Checkout PlaceHolder--
                <asp:ImageButton ID="CheckoutImageBtn" runat="server"
                    ImageUrl="https://www.paypal.com/en_US/i/btn/btn_xpressCheckout.gif"
                    Width="145" AlternateText="Check out with PayPal"
                    OnClick="CheckoutBtn_Click"
                    BackColor="Transparent" BorderWidth="0" CausesValidation="False" /> --%>



                <asp:Button ID="Button1" runat="server" OnClick="Button1_Click" Text="CheckOut" CausesValidation="False" UseSubmitBehavior="false" />



            </td>
        </tr>
    </table>



</asp:Content>

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;


using Celebreno.Models;
using Celebreno.Cart;

//for cart update
using System.Collections.Specialized;
using System.Collections;
using System.Web.ModelBinding;



namespace Celebreno
{
    public partial class ShoppingCart : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {

            //2- Display the total of cart by calling GetTotal() function(located in Actions_of_Cart class)
            //and then store the return value in a new variable, then dispaly it in a label
            using (Actions_of_Cart usersShoppingCart = new Actions_of_Cart())
            {

                //declare a new variable to store the total into it
                decimal cartTotal = 0;
                cartTotal = usersShoppingCart.GetTotal();

                if (cartTotal > 0)
                {
                    //Display Total in a label that has property " Enable ViewState = False"
                    //      ViewSate used
                    LblTotal.Text = String.Format("{0:c}", cartTotal);
                }
                else
                {
                    LblTotalText.Text = "";
                    LblTotal.Text = "";
                    //HtmlGenericControl
                    ShoppingCartTitle.InnerText = "The Shopping Cart is Empty";
                    //not yet needed
                   UpdateBtn.Visible = false;
                    //CheckoutImageBtn.Visible = false;
                }
            }



        }










        //1- decalre the select Method (used in GridView in Source Code) to return the value of..
        //..calling GetCartItems(), which is defined in Actions_of_Cart DB class
        public List<ItemsInCart> GetShoppingCartItems()
        {
            Actions_of_Cart actions = new Actions_of_Cart();
            return actions.GetCartItems();
        }













        //for cart update
        //this will loop throw the items in the cart and call update and remove button
        public List<ItemsInCart> UpdateCartItems()
        {
            using (Actions_of_Cart usersShoppingCart = new Actions_of_Cart())
            {
                String cartId = usersShoppingCart.GetCartId();

                Actions_of_Cart.ShoppingCartUpdates[] cartUpdates = new Actions_of_Cart.ShoppingCartUpdates[CartList.Rows.Count];
                for (int i = 0; i < CartList.Rows.Count; i++)
                {
                    IOrderedDictionary rowValues = new OrderedDictionary();
                    rowValues = GetValues(CartList.Rows[i]);
                    cartUpdates[i].ProductId = Convert.ToInt32(rowValues["ProductID"]);

                    CheckBox cbRemove = new CheckBox();
                    cbRemove = (CheckBox)CartList.Rows[i].FindControl("Remove");
                    cartUpdates[i].RemoveItem = cbRemove.Checked;

                    TextBox quantityTextBox = new TextBox();
                    quantityTextBox = (TextBox)CartList.Rows[i].FindControl("PurchaseQuantity");
                    cartUpdates[i].PurchaseQuantity = Convert.ToInt16(quantityTextBox.Text.ToString());


                    //TextBox quantityTextBox = new TextBox();
                    //quantityTextBox = (TextBox)CartList.Rows[i].FindControl("PurchaseQuantity");
                    //int a = 0;
                    //if (Int32.TryParse(quantityTextBox.Text, out a ))
                    //{
                      //cartUpdates[i].PurchaseQuantity = a;
                    //}

                }


                usersShoppingCart.UpdateShoppingCartDatabase(cartId, cartUpdates);
                CartList.DataBind();
                LblTotal.Text = String.Format("{0:c}", usersShoppingCart.GetTotal());
                return usersShoppingCart.GetCartItems();
            }
        }



        public static IOrderedDictionary GetValues(GridViewRow row)
        {
            IOrderedDictionary values = new OrderedDictionary();
            foreach (DataControlFieldCell cell in row.Cells)
            {
                if (cell.Visible)
                {
                    // Extract values from the cell.
                    cell.ContainingField.ExtractValuesFromCell(values, cell, row.RowState, true);
                }
            }
            return values;
        }




        protected void UpdateBtn_Click(object sender, EventArgs e)
        {
            UpdateCartItems();
        }









        protected void CheckoutBtn(object sender, ImageClickEventArgs e)
        {
            using (Actions_of_Cart usersShoppingCart = new Actions_of_Cart())
            {
                Session["payment_amt"] = usersShoppingCart.GetTotal();
            }
            Response.Redirect("Checkout/CheckoutStart.aspx");
        }

        protected void Button1_Click(object sender, EventArgs e)
        {
            using (Actions_of_Cart usersShoppingCart = new Actions_of_Cart())
            {
                Session["payment_amt"] = usersShoppingCart.GetTotal();
            }
            Response.Redirect("Checkout/CheckoutStart.aspx");
        }
    }
}

I have solved the problem of button event handling by adding these attributes. but when comes to other types of controls, these attributes cannot be included, so that problem is not solved.

<pre><asp:Button ID="UpdateBtn" runat="server" OnClick="UpdateBtn_Click" Text="Button" CausesValidation="False" UseSubmitBehavior="false" />