View Full Version : Excel cannot open file 'file.xlsx' because file format or extension is not valid

2015-05-13, 07:11 PM
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 file has not been corrupted and that the file extension matches the format of the file."
How to fix this error?

2016-01-21, 05:05 AM
I have found this to be the case when the file is given the wrong extension, e.g. when the file extension should be xls or csv. Try changing it to one or the other and see if you still have problems.