Want to save as Excel 2013 format (xlsx)

Question

Hello, I want to save the gridview to excel file. If I change the place of (.xlsx) to (.xls) , it is saved as 97-2003 excel format.

 

But now I change the (.xlsx).

It is saved as excel file.But I cannot reopen the excel file.

 

Can anybody help me in my problem?

Thanks a lot :-)

 

grvid.AllowPaging = false;

getgrid();

Response.Clear();

Response.AddHeader("content-disposition", "attachment;filename=file-name.xlsx");

Response.ContentType = "application/vnd.xlsx";

System.IO.StringWriter stringWrite = new System.IO.StringWriter();

System.Web.UI.HtmlTextWriter htmlWrite = new HtmlTextWriter(stringWrite);

grvid.RenderControl(htmlWrite);

Response.Write(stringWrite.ToString());

Response.End();

grvid.AllowPaging = true;

getgrid();