CODEWITHSUNDEEP
c#excel
ThEpRoGrAmMiNgNoOb
ThEpRoGrAmMiNgNoOb

Reputation: 1294

How to fix file format and extension don't match?

I created a code in c# which creates and saves excel file. The code can successfully create and save excel file, but when I open the excel file created, it displays a warning message telling:

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?

I am using the following code:

private void button1_Click(object sender, EventArgs e)
    {
        saveFileDialogSummary.Filter = "Excel Flie|*.xls";
        saveFileDialogSummary.FilterIndex = 0;
        saveFileDialogSummary.RestoreDirectory = true;
        saveFileDialogSummary.CreatePrompt = true;
        saveFileDialogSummary.Title = "Export Excel File To";

        Excel.Application ExcelApp = new Excel.Application();
        ExcelApp.Application.Workbooks.Add(Type.Missing);
        ExcelApp.Columns.ColumnWidth = 30;
        for (int i = 0; i < dataGridViewSummary.Rows.Count; i++)
        {
            DataGridViewRow row = dataGridViewSummary.Rows[i];
            for (int j = 0; j < row.Cells.Count; j++)
            {
                ExcelApp.Cells[i + 1, j + 1] = row.Cells[j].ToString();
            }
        }

        DialogResult res = saveFileDialogSummary.ShowDialog();
        if(res == DialogResult.OK){
            ExcelApp.ActiveWorkbook.SaveCopyAs(saveFileDialogSummary.FileName);
            ExcelApp.ActiveWorkbook.Saved = true;
            ExcelApp.Quit();
        }
    }

What should I do to avoid receiving that warning message?

Upvotes: 16

Views: 129958

Answers (4)

Jitendra G2
Jitendra G2

Reputation: 1206

The file extension .xls and .xlsx file contain different-different layout. the extension .xls use in version 2003 whereas then version .xlsx extension to be used.
You must export excel file to .xlsx format. It will support in all version as i used.

Add below DLLS into bin folder
1. ClosedXML.dll
2. DocumentFormat.OpenXml.dll

Code to Export to .xlsx

    DataTable dt = new DataTable(); 
    //Create column and inser rows
    using (XLWorkbook wb = new XLWorkbook())
    {         
                var ws = wb.Worksheets.Add(dt, Sheetname);
                HttpContext.Current.Response.Clear();
                HttpContext.Current.Response.Buffer = true;
                HttpContext.Current.Response.Charset = "";
                HttpContext.Current.Response.ContentType = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";
                HttpContext.Current.Response.AddHeader("content-disposition", "attachment;filename=" + p_FileName + ".xlsx");
                using (MemoryStream MyMemoryStream = new MemoryStream())
                {
                    wb.SaveAs(MyMemoryStream);
                    MyMemoryStream.WriteTo(HttpContext.Current.Response.OutputStream);
                    HttpContext.Current.Response.Flush();
                    HttpContext.Current.Response.End();
                }
     }

Upvotes: 3

Pushkar
Pushkar

Reputation: 1

The solution for "file format and extension don't match" is to close the work book**($workbook->close;)** at last after all necessary writings done on to the file.

I faced the same issue while opening the "XLS" file from mail. I created a file and inserted all my stuff init and without closing the workbook I send the mail as an attachment. Later I realized that have to close the workbook and send as an attachment.

Upvotes: 0

ninja_md
ninja_md

Reputation: 163

I know this problem may be resolved by now, but just trying to help you without modifying the code can still use .xls format in your's and suppress this warning while opening the file by setting a registry. Open reg edit, navigate to HKEY_CURRENT_USER\Software\Microsoft\Office\14\Excel\Security

Create a DWord with name ExtensionHardening and set the value to 0.

This might get your system vulnerable, but it is not a big deal when working in organisation network, at-least when you're sure of downloading the type of doc and source.

Upvotes: 11

ThEpRoGrAmMiNgNoOb
ThEpRoGrAmMiNgNoOb

Reputation: 1294

Just change the .xls to .xlsx if you have the latest office installed.

Upvotes: 10

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