Google recently introduced a new file format for their image uploads known as "WebPack". These image files are smaller than jpegs, while maintaining a better image quality. When downloading these files through Google Chrome, they will come through with the file extension ".webp".
This may be an issue when you or your customers are attempting to view files they've uploaded to a Product Options item. Currently, these files cannot be opened with most native image viewers (ie. Preview for Mac and File Viewer for Windows).
However, they are able to opened and previewed through Chrome without issue.
Note: Visit .WEBP File Extension (links to FileInfo) for more information on 3rd-party programs that can preview this file type.
Additionally, these files can be downloaded through another web browser as standard .jpeg files and opened through any image viewer.