Avoid warning in the time of exort excel file

The file format and extension of filename.xls don't match. The file could be corrupted or unsafe. Unless you trust its source, don't open it. Do you want to open it anyway?.

@model string

@{
    Layout = null;
    
    Response.Clear();
    Response.Buffer = true;
    Response.Charset = "";
    Response.ContentType = "application/vnd.xls";
    Response.AddHeader("content-disposition", "attachment;filename=SurveyReport.xls");
    Response.Flush();
    //Response.End();
 }