Solution 7: Open MS Excel in Safe Mode Solving the “ Excel cannot open because the file format is not valid ” problem can sometimes be as simple as booting your computer into Safe Mode . This is ...

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.

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.

Go to File > Open and select your Excel file. After opening the file in Excel Safe Mode, save it in a different format through File > Save As, selecting either .csv or .xls.

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.

If Microsoft Excel fails to recognize a file in the XLSX or XLS format, the data contained in the file could be corrupted. When you open a corrupted workbook in Excel, the program should ...

Greetings, I have a user who was working on an Excel 2007 file from a thumbdrive.. all of a suddem the file will not open and generates the following error: "Excel cannot open the file 'filename.xlsx' ...

"Excel cannot open the file because the file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file".

Excel cannot open the 'test.xlsx' because the file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file.

How to Open an XLS File in Excel. XLS files are Excel workbook files created in Excel 97 or Excel 2003. The 2007, 2010 and 2013 versions of the program use the XLSX format by default to save ...