I can't update the map version in my Garmin 830, show error
I had this same error on my Edge 830.
Unknown to me the version of Garmin Express on my desktop computer was out of date. I had imagined auto-update would take care of this kind of thing, but this time not.
I updated manually by downloading the freshest version of Garmin Express from the Garmin website and after installing this map-updates started working fine.