The Excel file will get saved to your PC with a .xlsx extension, which can be opened in any spreadsheet app, including Microsoft Excel, Apple Numbers, OpenOffice, LibreOffice, and more.

If Microsoft Excel fails to recognize a file in the XLSX or XLS format, the data contained in the file could be corrupted.

To fix the Unknown error trying to lock file in Teams, Excel, OneDrive, PowerPoint, SharePoint, etc, Office apps use these proven solutions.