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I have a Garmin GPSmap 76CSX. I also have the City Navigator and US Topo maps that are licensed to this unit. I prepared a gmapsupp.img file contain all of the maps from these map sets using MapInstall, but it wouldn't load onto my unit because I exceeded the file limit. I then used MapInstall to prepare a copy of the gmapsupp.img file needed and had it copied to a USB drive. From this drive I attempted to transfer the file to my unit Micro SD card. Part way through the transfer I get the the error message:
"The Finder can’t complete the operation because some data in “gmapsupp.img” can’t be read or written.
(Error code -36)"

What am I doing wrong??? Is there anyone out there who's had this problem and knows of a solution? Thanks in advance for any help you can give.



  • Boyd 1953 Points
    edited September 2016
    Is the file larger than 4gb? If so, it will not work because 4gb is the maximum allowable file size for the FAT32 filesystem that Garmin uses for their devices.

    Unfortunately, that is a problem for older GPS units like the 76csx (I have a 60csx, which is the same thing in a different case). Newer models allow multiple .img files, and they also have internal memory that can be used for maps. But you are limited to just one file named gmapsupp.img on the 76csx.

    Assuming that this is the problem, then about all you can do is select smaller portions of the topo and City Navigator maps, so that the file is less than 4gb.

    Also, when you say "US Topo", are you talking about the old version that was supplied on DVD and covers the entire US? Aside from the 4gb issue, you will not be able to load that entire map on your GPS due to another limitation of Garmin devices.

    Maps are broken down into smaller tiles called "segments". Your 76csx can only access approximately 2,000 of these segments but the entire US topo map consists of about 3,500 segments. So there is no way to load that entire map onto your GPS (well, you can "load" it, but it will not work properly). Again, the only solution is to choose a smaller portion of the map.

    And it is even worse, because the 2,000 segment limit is the total of ALL maps installed on your GPS, so you also have to consider how many segments the City Navigator map includes.

    Finally, I suggest that you use Mapsource instead of Basecamp/MapInstall. That is the software for which your 76csx was designed and I think it works better with these old devices. But it sounds like you are using a Mac and Mapsource is a Windows program. Do you have access to a PC that you could use for this instead? Or perhaps Parallels, etc on your Mac? You can download Mapsource here:

    One useful thing about Mapsource is that it will show you how many segments are included in the maps you have selected to send.
  • Boyd:
    Thanks so much for getting back to me on my problem. My file is not over 4GB, but close to it at 3.32. I've been trying to use MapInstall and that may be part of the problem so I'll D/L MapSource and attempt to load as many segments as possible on my unit. Thanks again for your help.
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