Got new firmware 4.60 on my Edge Explore today. Renamed the GUPDATE.GCD file to prevent install temporarily.
What is the changelog?
Renamed GUPDATE.GCD to temporarily prevent the installation. The rename you have to do after the synchronisation by Garmin Express and before you safely detach the Explore from the PC.The Explore is still in mass storage mode then.
As soon as changelog is published and I'm confident, also from user experiences, that installation of the update is safe, then I rename the file back to GUPDATE.GCD and activate the update through the menu on the Explore: System / About / Software Update