1] Check the file extension Check the file extension to make sure the file you’re trying to open is a type of Excel file. Sometimes while renaming files we accidentally mess up with the file ...

Excel users who have been using the platform for over a decade would be aware of the .xls file extension from back in the day. Over the years, newer versions of Excel started using the .xlsx ...

6] Change the file extension of your Excel workbook file Try changing the extension of the Excel workbook file from .xlsx to .xls (or vice versa) and see if it works.

The Excel team has made a change in the behavior of certain file types to increase security. This change came in the security updates KB3115262, KB3170008, and KB3115322.

Tips Word and Excel used the DOC and XLS file extensions, respectively, by default from 1997 until 2004. From 2004 onward, Microsoft made DOCX and XLSX the default file extensions.

Excel displays a warning message that the file format and extension don’t match (HTML table and XLS), but allows the user to open the file anyway. Today, users reported that these reports no ...