Re: Locking cells in Excel Online? Is it possible?

If you want to keep your data locked away from others, you can do so using Microsoft Excel Online.

1. First, open Microsoft Excel Online.
2. Then click the File tab and select Options.
3. On the Options dialog box, click the Protection tab.
4. Under Lock Cells, select the lock type that you want to use.

For more detailed article you may check out this blog post: https://quickenterprisesupport.com/excel-could-not-open-the-data-file/