Excel无法打开文件，因为文件格式或文件扩展名无效。 确认文件未损坏

Question

I am trying to export into excel with xlsx and xls format but getting this error when trying to open the file. Excel cannot open the file 'tms.xlsx' because the file format or file extension is not valid. Verify that file has not been corrupted and that the file extension matches the format of the file.

 public static void ExportToExcel(object allLists, string fileName, string driverName) { try { grid.DataSource = allLists; grid.DataBind(); RowCreated(); Header(fileName, driverName); HttpContext.Current.Response.ClearContent(); string FileName = String.Format(fileName + "-{0}", DateTime.Now.ToString("dd/MMM/yyyy")); HttpContext.Current.Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"; HttpContext.Current.Response.AddHeader("content-disposition", "attachment; filename=" + FileName + ".xls"); StringWriter sw = new StringWriter(); HtmlTextWriter htw = new HtmlTextWriter(sw); //Applying style to grid view header cells for (int i = 0; i < grid.Rows.Count; i++) { for (int J = 0; J < grid.HeaderRow.Cells.Count; J++) { if ((grid.Rows[i].Cells[J].Text.Contains("-y@llow"))) { grid.Rows[i].Cells[J].BackColor = System.Drawing.Color.FromArgb(255, 255, 179); var val = Convert.ToString(grid.Rows[i].Cells[J].Text); if (val != null && val != "") { if (val.Contains("-y@llow")) { val = val.Replace("-y@llow", ""); grid.Rows[i].Cells[J].Text =Convert.ToString(val); } } } else if((grid.Rows[i].Cells[J].Text.Contains("-gr@en"))) { grid.Rows[i].Cells[J].BackColor = System.Drawing.Color.FromArgb(159, 223, 159); var val =Convert.ToString(grid.Rows[i].Cells[J].Text); if (val != null && val != "") { if (val.Contains("-gr@en")) { val = val.Replace("-gr@en", ""); grid.Rows[i].Cells[J].Text = Convert.ToString(val); } } } } } for (int i = 0; i < grid.HeaderRow.Cells.Count; i++) { grid.HeaderRow.Cells[i].Style.Add("background-color", "#337ab7"); grid.HeaderRow.Cells[i].Style.Add("color", "white"); } grid.RenderControl(htw); HttpContext.Current.Response.Write(sw.ToString()); HttpContext.Current.Response.End(); } catch (Exception) { //Response.End() will generate exception so, do not throw the exception here. //Response.Write(Ex.StackTrace); } } 

Answer 1

Please check content type and extension. You currently have .xls and application/vnd.ms-excel . The stated xlsx requires the respective extension and

ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"`

To add a bit of context I use this as follows in an controller method that returns an ActionResult

ActionResult ExportAsExcel(object input)
{
    var fileData = ExcelExport.CreateExcelContent(input);

    if (fileData == null || fileData.Length == 0)
    {
        ViewData["Message"] = "Could not create export file";
        View("Error");
    }

    // File is of type Controller.File
    return File(fileData, "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", "export.xlsx");
}