Cannot Unlock Maps

I just updated my maps on my Montana 750i using Garmin Express but I do not see the 2024 City Navigator Map on my device.  Also, when I turn on my device, I get the error message "Cannot Unlock Maps".  This is not a third-party map, it came with the update from Garmin.  Any idea why this is happening?

  • Hi Leslie...It did not work.  I get the exact same error messages.  Apparently there is insufficient room on the device according to other users.  Right now, my unit is basically a brick because I cannot use it with maps, it will not update.  How do we fix this?  How can I uninstall the map and try re-installing from there?  

  • See the answers in your other thread.

    Please do not cross-post the same content in multiple threads. I am not going to lock this one because is engaged here.

  • Perhaps the 16.50 update solves your prob:

    Fixed potential “Can’t Authenticate Maps” prompt“

  • Hi Volker.  Thank you for replying.  Unfortunately, I just updated and the update worked out fine, then I inserted my previous SDCards containing the 2011 version of City Navigator for SE Asia, Europe, and USA and none of them work.  I get that exact message: "Can't Authenticate Maps".  Now I am afraid the purchase additional maps from "TheGPSStore.com" which is where I purchase my previous maps.  They worked fine in both my older Garmin Oregon and Montana.  The SD cards are transferrable from one unit to another and are not locked to any one unit.  Funny, because I am using a Japan map and the manufacturer is definitely not Garmin.  The Japan map is produced locally in Tokyo by a company called UpUpDown and the maps worked in all of my Garmin devices including my current unit the Montana 750i.  Works like a charm.  Any ideas?

  • Sorry, I just wanted my problem to get widest dissemination.  I finally got things to work.  Insufficient space seems to be the problem.  So, I deleted the CityNavigator 2024 map, and reinstalled it on an MicroSD and works fine.  I do not mind swapping out cards since I would only have to do so when I travel.  Any suggestion on why I still get the "Can't Authenticate Maps" error message when attempting to load my older CityNavigator maps for SE Asia and Europe.  The cards are dated 2011 and worked in both my Garmin Oregon and Montana 650t.  The MicroSD cards I purchased from "TheGPSStore.com" but are native Garmin maps and are not locked to any one unit.  They are old from 2011 but I cannot imagine that being the cause.  Funny, because I have a Japan map loaded on a MicroSD card.  The map is third-party and definitely not from Garmin, instead it is a map produced locally in Tokyo by a company called UpUpDown and it worked in both my previous Garmin products plus it works like a charm in my current Montana 750i.  Any suggestions?  The website where I want to purchase my new SE map and Europe map insists that their maps will work in my Garmin 750i, but now I am reluctant to purchase from them.  Any idea where I can purchase these maps that is a reliable company and will ship to Japan?  Your help is always appreciated.  Thank you.  One more thing, I just updated my Montana 750i to the very latest software/firmware and it still does not load the maps.

  • I think you should contact the Garmin support and ask, why the old Garmin maps purchased on sd cards don’t work for your 750i, perhaps the age of the sd cards (2011) is somehow a problem for the 750i? I don’t think it is an issue caused by the shop you bought the maps (and they have worked for your other Garmin handhelds).