If you cannot open an Excel file and see Excel cannot open the file because the file format or extension is not valid error, see this post.

To fix the Excel file format does not match extension error, trying opening the spreadsheet with the Open and Repair option or changing its file extension.

1. Change the Extension Manually When the file extension doesn’t match the format, changing it manually helps Excel read the file correctly. Adjusting the extension (e.g., from .txt to .xlsx) aligns ...

With the Excel extension is not valid error, try starting the app in Safe Mode, repair the workbook or open the file in another program.

Every now and then, when I try opening an Excel file, I get a message saying that "Excel cannot open the file 'file.xlsx' because the file format or the file extension is not valid. Verify that the ...

How to Recover a Microsoft Excel File That Is Not in a Recognizable Format. If Microsoft Excel fails to recognize a file in the XLSX or XLS format, the data contained in the file could be corrupted.

[Bug]: Excel cannot be open the file because the file format or file extension is not valid #3987 Closed ruuddeenen opened on Aug 31, 2023 ...