The current, an only supportable version of Office Online Server is Office Online Server, April 2017 release. This version will support installation on Windows Server 2016. Other improvements include:
- Performance improvements to co-authoring in PowerPoint Online.
- Equation viewing in Word Online.
- New navigation pane in Word Online.
- Improved undo/redo in Word Online.
- Enhanced W3C accessibility support for users who rely on assistive technologies.
- Accessibility checkers for all applications to ensure that all Office documents can be read and authored by people with different abilities.
You will need to uninstall the previous version of Office Online Server before installing the April release.
For more information about the April 2017 release refer to: https://blogs.office.com/2017/04/18/office-online-server-april-2017-release/Tags Office, OOS, SharePoint