This week I was digging in to Share Point. While reviewing the basics, a user discovered an issue with one of her excel sheets. At first the user received an error stating “The workbook could not be opened.” After testing by double checking access and attempting to re-upload the file I was dumbfounded. Then when trying to open the file I got a completely different error message describing the real problem. “We’re sorry. We can’t open the workbook in the browser because it uses these unsupported features: Sheet Protection.” At that point the issue was clear. Someone had password protected one of the sheets on the workbook.
The solution was to download the file, un-protect it, and then upload the file again. To un-protect a file in Excel 2010/2013 select the review tab and select un-protect sheet. A password may be needed if the user who protected it added a password. This resolved the issue after upload and the users were able to view the file again.