Unable to open Excel file

Occasional Visitor

Re: File "Books ti read.xlsx" (sic)

Error message: 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.


Using Office 365, Windows 10

2 Replies


Since this is probably a template, I would first recommend changing the file to .xltx format (meaning the file extension) instead of .xlsx format.


If this does not help and the error only occurs with this file, I recommend following this link with the attached steps.

Repair a corrupted workbook



Hope I was able to help you with this info & link.



I know I don't know anything (Socrates)


Sometimes users are troubled with different types of runtime errors by which they are unable to access their Excel files. One of the Excel errors is “File Error: Data May Have Been Lost”. 

In order to repair the damaged excel file you have to perform the following steps:


  1. Open the excel file.

  2. Now select the corrupted workbook that you want to open.

  3. Then click on Open and Repair by clicking the arrow next to the Open button.

  4. Now perform any one of the following:

  • Click on Repair in order to recover the data from excel.
  • To extract values and formulas from the workbook when an attempt to repair the workbook is not successful, click Extract Data.



I hope this method could help to recover the damaged excel file.


Best Regards,