SharePoint Excel error - The workbook cannot be opened because it contains the following features that are not supported by Excel in the browser

SharePoint along with Office Web Apps (OWA) or Excel Services provides a feature where users can open Microsoft Office documents within the browser.

Though this is a very handy and useful feature, there are some limitations.

Sometimes while opening an excel file, you will come across this error message

The message says clearly says that SharePoint does not support certain features when opening excel in the browser -

The workbook cannot be opened because it contains the following 
features that are not supported by Excel in the browser:
• Data validation
• Sheet protection
Would you like to try and open this file in Excel?
Learn more about unsupported features

Clicking on "Learn more about unsupported features" may bring up a popup window saying "Need assistance ?" asking you to type what you want. Not useful at all. But SharePoint at least provides an option asking to open the file in Excel. Good if you have MS Office installed.

1. Click Yes on the message box to open the file in Microsoft Excel and work on the local machine
2. Use the 'open with explorer view' option to open the file directly and not within the browser
3. Change the setting for document library containing excel file forcing SharePoint to open the file in the client application
4. Remove unsupported features from an excel sheet like data validation and retry. It Will work, but I'm not sure who would want to do that.

You can search MSDN for getting a list of supported and unsupported excel editing features with Excel Services and Office Web Apps.