Exporting HTML Table to Excel Extension Issues

Question

I'm working on a page that exports an HTML table to an Excel spreadsheet by using the markup listed below to create the spreadsheet. However, whenever a new Excel document starts, I get a warning that "ExcelDocName.xls's file format and extension don't match. The file might be dangerous or corrupt." Excel cannot open the file "ExcelDocName.xlsx" because the file format or file extension is invalid, despite the fact that I assume this is happening due of the.xls extension. How should I change this markup to fix these problems?

<!DOCTYPE html><html  xmlns:o='urn:schemas-microsoft-com:office:office' xmlns:x='urn:schemas-microsoft-com:office:excel' xmlns='http://www.w3.org/TR/REC-html40'> 
<head>  
   <meta http-equiv=Content-Type content='text/html;charset=windows-1252'><meta name=Generator content='Microsoft Excel 11'> 
   <meta name=ProgId content=Excel.Sheet> <meta name=Generator content='Microsoft Excel 11'> 
<style> 
<!--table @page{}-->
</style>
<!--[if gte mso 9]><xml> <x:ExcelWorkbook><x:ExcelWorksheets><x:ExcelWorksheet>  <x:Name>Sheet1</x:Name>    <x:WorksheetOptions><x:Panes> 
</x:Panes></x:WorksheetOptions></x:ExcelWorksheet></x:ExcelWorksheets><x:ExcelWorkbook></xml><![endif]--> 
</head>
<body><form method='POST' action='" &APSPostName&".asp' name='frmExcel'></form>    
    <!-- Table HTML goes here -->
</body></html>

The following is included after the markup is created.

Response.ContentType = "application/vnd.ms-excel"
Response.AddHeader "Content-Disposition", "attachment; filename="&ExcelName&".xls"

narikkadan · Answer 1 · Nov 14, 2022

In my application, I'm experiencing a similar issue. I've just discovered that this is a problem with Microsoft Excel, not the file itself. Starting with Excel 2007 and up to the most recent version of Excel 2016, you cannot open HTML material using Excel unless it has been saved with the.html extension.

Although you can open the file without any issues with Open Office or Libre Office if you save it with the.xls extension, Microsoft Excel will give you errors when you try to open it (2007 - Current)

Solution:

Save the file as a .html extension and inform the user to open it with Microsoft Excel (Once opened they can save it as an excel document).
Save the file with a .xls extension and inform the user to open it with Open Office or Libre Office. to avoid the annoying error.
Save the file with a .xls extension and inform the user about the error and inform them to ignore the error and click yes when it pops up.