Firstly, make sure that you are NOT trying to expand/unzip the IMG file (the map); this will not work as the map file is NOT a 'Disc Image' no matter what your Mac says. It is the map file ready to be used on a Garmin device or MicroSD card. The map file will NOT open/run/execute or display on your computer.
There is a confirmed bug in MacOS Unarchiver (yet another issue with Macs, so much for them being easy to use!).
You will normally only see this issue when you are using Finder or Unarchiver to try and open the ZIP. The other rare possibility is that the downloaded ZIP file is incomplete, please try the solutions below, before downloading the ZIP file again.
You can successfully unzip via another file manager, such as ForkLift, Transmit, Commander One, or Path Finder instead. These other file mangers do not suffer from the same bug as the inbuilt Finder/Unarchiver app. Otherwise just use the command line unzip program (via a terminal), see below:
Open Terminal from Applications/Utilities (or use Spotlight to find it).
Type unzip followed by a space; drag the file in question onto the Terminal window… the name & path should be completed for you. Press enter/return.
If there are no errors, the unzipped content should be in your Home folder (Users/Your name).
There are a number of third party ZIP apps, such as iPackr, Extractor, RAR Extractor Lite, and Keka (some of these are available on the App Store for FREE) that handle ZIP files correctly.
Related Articles
Why can’t I unzip the ZIP file on a Mac, I get “Unable to expand “.zip” into “”. (Error 1 -= Operation not permitted)”, Error 79, or some other error?
There is a confirmed bug in MacOS Unarchiver (yet another issue with Macs, so much for them being easy to use!). You will normally only see this issue when you are using Finder or Unarchiver to try and open the ZIP. The other rare possibility is that ...
Error -36 When Copying File to MicroSD Card (Mac)
If you get an Error -36 message when trying to copy the map file to a MicroSD card in your Mac, the issue is due to a bug in Mac OSX (as usual), and it still isn't fixed! You may find this article on the cause of the error message and how to fix it ...
How do I check to see if the ZIP file is complete?
If the downloaded file ends in .download (Safari) or .part (Firefox) or .crdownload (Edge/Chrome) then the file is either still downloading (and you need to be patient whilst it completes the download) or incomplete, if the download has ...
BaseCamp - "Valid Chart Product Not Found" or "an error occurred when attempting to use..."
First Things: If the map is not working on either the internal storage or a MicroSD or SD card in the Garmin device, then the issue is NOT with BaseCamp; either the card or the map has become corrupted or is not correctly installed. If this is the ...
Computer says the “Disc Image File is Corrupted” or “Not Mountable”, etc.
The file is probably fine, it is just that you are trying to open, run, launch or execute the map file on a computer, it isn’t designed to work on a computer, just on a Garmin GPS device. So, on a windows PC, if you see a message telling you that the ...