You would have thought that the amount of money that this watch costs, Garmin would get it right. Mine's done this since I first updated it and I've never found a solution. Do all the maps work as a result of this message? I don't know. Certainly the UK and Europe do. Not tried The States yet.
You should still be able to update the worldwide Golf courses on an Apple Mac or a Windows computer as long as both have a new enough version of their operating system. Please ensure your Mac meets the OSX 10.11 or newer requirements for Garmin Express.
If so, and you continue to have updating issues on your Mac, please highlight my name and send me a Private Message.