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.

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 ...

One common challenge that users face is encountering the error message Excel cannot open the file because the file format or file extension is not valid .

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.

To fix the Excel file could not be found check the spelling error, try reducing the Excel file's path length and deactivating add-ins.

If Microsoft Excel opens a Blank screen when you open an existing file, then you can stop Excel from opening a Blank workbook or sheet.

Expected Behavior I'm trying to open via openxlsx the simple Excel file, whic was generated by Java (apache POI library). This is the code I use: # Test Excel ## Needed library - if you do not have ...