Forum Discussion
Excel cannot be open the file 'filename.xlsx' because the file format or file extension is not valid
It was probably not saved as an Excel file.
Before repairing, please change all Excel files to All files (*. *) .
If this is not the case either, it is very likely that it will no longer be possible to restore the file.
Additional Info:
Repairing a corrupted workbook
Thank you for your understanding and patience
Nikolino
I know I don't know anything (Socrates)
In my case, the same problem occured after I moved my One Drive folder to another disk, because the original location had no more space.
After moving, the files in the new place became outdated, probably because local files were not synchronized with the cloud.
I deleted the original One Drive folder, and the system asked for a complete deletion, because the folder was too big.
After knowing that some of my spreadsheets were outdate, I recovered them using third party software, but Excel doesn't open them, the message is the same in this post.
I've tried all solutions posted here, and also all solutions proposed by Microsoft, but I had no success. It's frustrating because I can see that the size of the recovered file is a little bigger than the outdated file, what is coherent. Also, the same problem occurs with all spreadsheets restored. I still think that this thing is related to One Drive.
Finally, I tried to attach one of the files and received the error message:
- The attachment's caixa 2021.xlsx content type (application/vnd.openxmlformats-officedocument.spreadsheetml.sheet) does not match its file extension and has been removed.