Exporting ASP.Net GridView to Excel file is blank using C# and VB.Net

Hi All, I have a GridView with 10K + data fetching from SQL Server and i have to export to excel...I have used all the code written in stackOverflow,C# cornber,ASP forums...but the problem arise when i open message popup saying the file you are trying to open is in diff. format corrupt.......something like this...i want a solution when i click export button file should be download and message should not be popup...please help i stuck from 3 days

using ClosedXML.Excel;
using System.IO;
public partial class GridExp : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            BindGrid();
        }
    }
 
    private void BindGrid()
    {
        DataSet ds = clsSQLExecute.Exec_Dataset_string("select * from UserDetails");
        if (ds != null && ds.Tables[0].Rows.Count > 0)
        {
            gv1.DataSource = ds;
            gv1.DataBind();
        }
        else
        {
            string Msg = string.Empty;
            Msg = "No record Found !";
        }
    }
    protected void btnexport_Click(object sender, EventArgs e)
    {
        XLWorkbook wb = new XLWorkbook();
        Response.Clear();
        Response.Buffer = true;
        Response.Charset = "";
        Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
        Response.AddHeader("content-disposition", "attachment;filename=ExportExcel.xlsx");
        MemoryStream MyMemoryStream = new MemoryStream();       
        wb.SaveAs(MyMemoryStream);
        MyMemoryStream.WriteTo(Response.OutputStream);
        Response.Flush();
        Response.End();
    }
}