A growing number of users are experiencing issues concerning Mac OS X 10.6 Snow Leopard's handling of .dmg files. Since upgrading to Snow Leopard these users are not able to mount the files or run ...

macOS Monterey version 12 is a stable, lightweight upgrade that works great on older Macs, and you can use the direct DMG or ISO links to download, install, upgrade, or downgrade your system easily.

Well, there is room for X to be told to handle each file a separate way, even though they have the same extension. Assuming the file itself is okay, use the Get Info pane to tell the OS to use Disk ...