[SOLVED] Excel cannot be open the file 'filename.xlsx' because the file format or file extension is not valid

[noyaus]

Hi Guys,
I have an issue with my Excel which is part of my Microsoft 365 Subscription. So what happens is whenever I try to open a document called 'A' on my USB I get the error:
"Excel cannot be open the file 'filename.xlsx' because the file format or file extension is not valid." This issue only happens to the file 'A' no other excel workbooks are affected by this. On the other hand, I have the exact same copy of that file saved locally onto my computer in which I can work on and update etc. without it giving me an error. What can I do to fix this issue.

I am currently using Windows 10 Home 20H2.

 

[Phillip Corcoran]

"File extension not valid" could be a spurious error message.
The copy on the USB device may be corrupted, or the USB device itself may be faulty.

Try this:

Create a new folder (any name) on the USB device.
Copy the good file from your computer to the new folder on the USB device.
Now try to open that new copy on the USB device.

 

[Grobe]

This can happen if omit using "safe removing hardware" -thing in Windows (also found in file explorer when right click on the usb stick drive symbol).

 

[noyaus]

This can happen if omit using "safe removing hardware" -thing in Windows (also found in file explorer when right click on the usb stick drive symbol).

So dou reckon I should not be using this?
Usually when i eject I eject using that.

 

[Grobe]

So dou reckon I should not be using this?
Usually when i eject I eject using that.

Yes - use the reject option , the proper way of removing usb storage devices.