Datatable exporting to Excel showing Error Message in Excel File

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C#

ASP.NET

After Exporting the Data from Datatable to Excel sheet shows this Error while Opening.

The file format and extension of '.xls' don't match.The file could be corrupted or unsafe

Below is the code used to Export to Excel

Datatable dt=BindData();
GridView GridView1=new GridView();

if (dt.Rows.Count > 0)
{
Response.ClearContent();
Response.Buffer = true;
Response.AddHeader("content-disposition", string.Format("attachment; filename={0}", "Requisition.xls"));
Response.ContentType = "application/ms-excel";
System.IO.StringWriter sw = new System.IO.StringWriter();
HtmlTextWriter htw = new HtmlTextWriter(sw);

GridView1.AllowPaging = false;
GridView1.DataSource = dt;
GridView1.DataBind();

//Change the Header Row back to white color
GridView1.HeaderRow.Style.Add("background-color", "#FFFFFF");
//Applying stlye to gridview header cells
for (int i = 0; i < GridView1.HeaderRow.Cells.Count; i++)
{
GridView1.HeaderRow.Cells[i].Style.Add("background-color", "#507CD1");
}

int j = 1;
//This loop is used to apply stlye to cells based on particular row
foreach (GridViewRow gvrow in GridView1.Rows)
{
gvrow.BackColor =System.Drawing.Color.White;
if (j <= GridView1.Rows.Count)
{
if (j % 2 != 0)
{
for (int k = 0; k < gvrow.Cells.Count; k++)
{
gvrow.Cells[k].Style.Add("background-color", "#EFF3FB");
}
}
}
j++;
}

GridView1.RenderControl(htw);
Response.Write(sw.ToString());
Response.End();

}