We don't know a great deal about Macs. We had to make an installer, and were told to try a .dmg

So we put together version 1, and it seemed to work. We had one application file, which had our icon, and one folder. The user was instructed to drag these into the Applications folder, of which there was the Mac version of a shortcut in the dmg.

Then we were told we needed to update files, and assured that we could do so via drag-and-drop. So we did; we dragged them into the folder in the dmg. We tested it (on the computer we were using to edit the dmg) and it seemed to work. So we burnt it onto a disk (along with a windows installer that actually works!).

I've just gotten an email from the recipient. She's got a Mac laptop. She inserted the disk, doubleclicked on it, doubleclicked on the .dmg, and got a Warning: no mountable file systems. Screenshot:

enter image description here

I have the dmg (not on a disk) and am able to open it with no difficulty.

How can we get it to work for our recipient?

  • Use zip. Many Mac developer shops (e.g. Panic) switched to application distribution using zip archives a while ago. Also, autorun.inf does not work on Mac OS X.
    – Daniel Beck
    Oct 21, 2010 at 9:24
  • autorun.inf is for the Windows installer I mentioned. We had both on one disk. Are you able to tell me how to make the right sort of zip archive? Are they easy for the user to unzip and install? This is a program for kids. Oct 21, 2010 at 22:32
  • @dragon Sorry, didn't see your comment (use @Username when replying to someone so they get notified).Can't see the Windows binary in the screenshot, therefore the tip. Check out Panic's website and download e.g. Transmit and have a look: this is commercial software that's as easy or difficult to install as distributed via DMGs. They switched in fact because it's easier if users have no idea what they're doing. Since you mention that both a folder an an application need to be moved, it could be a little more difficult. Can you elaborate on the structure of your DMG's contents?
    – Daniel Beck
    Oct 25, 2010 at 13:51
  • @dragon Also, how are you creating .dmg files if not on a Mac?
    – Daniel Beck
    Oct 25, 2010 at 13:52
  • @Daniel We made the .dmg on a Mac in one of the labs at uni, but were trying to burn it from a Windows computer. We finally got it working... by doing exactly the same thing again. In effect, we burnt the same disk three times; #1 and #3 worked; #2 didn't, and I honestly couldn't tell you why. In any case, I don't think I would try to use a .dmg again. They seem terribly unreliable. Oct 26, 2010 at 8:10

2 Answers 2


Are you saving the disk image as read-only before putting it on the disk? If you're burning a read/write image to a read-only media like DVD I could imagine that there might be problems.

  • This would be better suited as a comment to the original question.
    – Daniel Beck
    Oct 25, 2010 at 13:45

In my experience, that "no mountable file systems" error indicates a corrupted disk image. Is it possible it didn't get burned correctly/completely (try comparing file sizes for the original vs. the copy on the CD)? Did you dismount the image (or better yet, convert it to read-only or compressed format) before burning it? If it was mounted when you burned it, it's possible there were unsaved changes and it was burned in an inconsistent state...

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