We’re adding support for # and % as supported characters in file and folder names across document libraries in SharePoint Online and OneDrive for Business. We’ll begin rolling this feature out in October.
This feature has been available for opt-in since earlier this year. We’ll begin turning this on-by-default to existing organizations, in October. The update will be completed by the end of March 2018.
This message is associated with Office 365 Roadmap ID 14656.
How does this affect me?
This will allow you to create, store, and sync files containing # and % characters whether those characters are used as a prefix or suffix to the file or folder name.
What do I need to do to prepare for this change?
This feature has administrative controls to enable and disable. If you wish more time to prepare for this change, you should configure this feature to be off-by-default, by end of September.
Please click Additional information to learn more.