Re: Excel cannot be open the file 'filename.xlsx' because the file format or file extension is not valid

I face the same issue.

I have a xslx file with the name Schedule 2025. I have shared it with my team. I can open it through Sharepoint but I cannot open it from my pc.

I have tried to provide full access but problem remains. The file does not have any weird formats inside. It's quite simple. I don't want to delete the file and create a new one. I just want this one repaired.
The open and repair option is not helpful as I get the same error message