The warning indicates that the Player's web-browser is either:
a. So old it doesn't support the local storage functionallity required by the SugarCube engine.
b. Is being run in a mode / way that restricts access to the storage functionallity required.
a. You can get this warning if the web-browser has been configured to disable cookies.
b. Microsoft Edge will show a simular warning message if the Player is trying to view a copy of your Story HML file from their local hard-drive.
1. Did you personally recieve this warning, or was it reported by another person?
2. Which web-browser (brand and version) was being used, and which mode was it being run in, when the warning occured?
3. Was the Story HTML file being accessed remotely on a web-server, or was it being access locally on from a hard-drive?