Really? Which satnav do you have, Garmin have a history of supporting devices for tens of years. What files are you trying to update?
Aaagh! Don't get me started. I have an etrex, and a Nuvi for the car. The Nuvi, despite every suggestion on the Garmin website, and youtube, will not update the maps. Comment from Garmin- "Upgrade to a newer model." No thanks.
The etrex is so cumbersome to use , plus it will not do a complete reset despite many tries, I will get a better type when I can afford it, maybe never. My unit does not have extra memory capability either, restricts the amount of maps I can consult.
I like nice simple tools like map and compass, if I have to mess around plugging in to my laptop, loading files, software updates, generally faffing about with technology that I thought was designed to make life easier, then I'm not that interested.