[Solved] ASP.Net GridView OnRowUpdating Error: Object reference not set to an instance of an object

I have a users list with some module name like that

UserID  UserName     Animal  Breading  Health   Stock        Action      

1           ABC               True     False       True      False        Edit

2          SKY                 False    True        False     True        Edit

Now I want to update values inside these gridview using event onRowUpdating. I wrote the following code.

Now, when I update the values it shows me error.

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

how to get solution solution pls.

HTML

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="false" DataKeyNames="UserID" Class="table table-striped table-bordered table-hover"
    OnRowEditing="OnRowEditing" OnRowCancelingEdit="OnRowCancelEdit" OnRowUpdating="OnRowUpdating">
    <Columns>
        <asp:CheckBoxField DataField="IsSelected" HeaderText="Action" />
        <asp:BoundField DataField="UserName" HeaderText="User Name" ItemStyle-Width="150px" ReadOnly="true" />
        <asp:BoundField DataField="Password" HeaderText="Password" ItemStyle-Width="150px" ReadOnly="true" />
        <asp:CheckBoxField DataField="Animal" HeaderText="Animal" ItemStyle-Width="150px"/>
        <asp:CheckBoxField DataField="Breading" HeaderText="Breading" ItemStyle-Width="150px"/>
        <asp:CheckBoxField DataField="Milk" HeaderText="Milk" ItemStyle-Width="150px"/>
        <asp:CheckBoxField DataField="Stock" HeaderText="Stock" ItemStyle-Width="150px"/>
        <asp:CheckBoxField DataField="Accounts" HeaderText="Accounts" ItemStyle-Width="150px"/>
        <asp:CheckBoxField DataField="Employee" HeaderText="Employee" ItemStyle-Width="150px"/>
        <asp:CheckBoxField DataField="Reports" HeaderText="Reports" ItemStyle-Width="150px"/>
        <asp:CommandField ShowEditButton="true" HeaderText="Update" ItemStyle-Width="100px" />
    </Columns>
</asp:GridView>

protected void OnRowUpdating(object sender, GridViewUpdateEventArgs e)
{
    GridViewRow row = GridView1.Rows[e.RowIndex];
    int UserId = Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Values[0]);
     
    //Get the checked value of the CheckBoxField column.
    bool isSelected = (row.Cells[0].Controls[0] as CheckBox).Checked;
    bool Animal = (row.Cells[3].Controls[0] as CheckBox).Checked;
    bool Breading = (row.Cells[4].Controls[0] as CheckBox).Checked;
    bool Milk = (row.Cells[5].Controls[0] as CheckBox).Checked;
    bool Health = (row.Cells[6].Controls[0] as CheckBox).Checked;
    bool Stock = (row.Cells[7].Controls[0] as CheckBox).Checked;
    bool Accounts = (row.Cells[8].Controls[0] as CheckBox).Checked;
    bool Employee = (row.Cells[9].Controls[0] as CheckBox).Checked;
    bool Reports = (row.Cells[10].Controls[0] as CheckBox).Checked;
    //bool Graphs = (row.Cells[11].Controls[0] as CheckBox).Checked;
    string constr = ConfigurationManager.ConnectionStrings["ConStr"].ConnectionString;
    using (SqlConnection con = new SqlConnection(constr))
    {
        using (SqlCommand cmd = new SqlCommand())
        {
            cmd.CommandText = "UPDATE tblCreateUsers SET [IsSelected] = @IsSelected, [Animal] = @Animal, [Breading] = @Breading, [Milk] = @Milk, [Health] = @Health, [Stock] = @Stock, [Accounts] = @Accounts, [Employee] = @Employee, [Reports] = @Reports WHERE UserID=@UserID"; //, [Graph] = @Graph
            cmd.Connection = con;
            con.Open();
            cmd.Parameters.AddWithValue("@UserID", UserId);
            cmd.Parameters.AddWithValue("@IsSelected", isSelected);
            cmd.Parameters.AddWithValue("@Animal", Animal);
            cmd.Parameters.AddWithValue("@Breading",Breading);
            cmd.Parameters.AddWithValue("@Milk",Milk);
            cmd.Parameters.AddWithValue("@Health",Health);
            cmd.Parameters.AddWithValue("@Stock",Stock);
            cmd.Parameters.AddWithValue("@Accounts",Accounts);
            cmd.Parameters.AddWithValue("@Employee",Employee);
            cmd.Parameters.AddWithValue("@Reports",Reports);
            //cmd.Parameters.AddWithValue("@Graph", Graphs);
            cmd.ExecuteNonQuery();
            con.Close();
        }
    }
    GridView1.EditIndex = -1;
    this.BindGrid();
}