you need MacOS : Mac OS High Sierra, Mojave
For this error the Internet recommends
- try downloading the dmg again
Reboot your Mac if you haven’t already tried that. Apparently there is an issue sometimes after opening too many dmg files, that is fixed with a reboot.
Try mounting the DMG on the command line in Terminal . We will at least get some sort of useful error message to go on if it still fails:
- Open Terminal: In Spotlight, the search magnifying glass at the upper right corner of your screen, search for Terminal, and press enter to open the Terminal app.
hdiutil attach into the terminal. Don’t press enter yet.
- Drag the dmg file from your Finder window onto the Terminal window and let go. This will fill in the location of the dmg file into your Terminal window.
- Press enter.