Disk image not recognized during macOS 10.8 to 10.12 update

Question

Disk image not recognized during macOS 10.8 to 10.12 update

This has to do with the "disk image could not be opened" message (macos 10.8) but I cannot find any steps that work for the specific issue I'm having.

I am trying to update my old iMac (because it still functions better than some new computers and various other things). I was last running the most hacked together install of windows 11 that I think there has ever been, I decided that I actually wanted to use this thing and am trying to get it up to 10.15 (the latest version it's compatible with) and to do so, I first had to install 10.8. the issue arises when I try to update to 10.12 (for various reasons I cannot go directly to 10.15) so after managing to get a functioning browser installed, I got the .dmg for 10.12 installed and it will not open. It keeps popping up with "disk image could not be recognized"

I have tried everything I could for a "cannot open" message but nothing has the specific error message I'm getting. This is the exact same file that I've downloaded 4 times on both this computer and my laptop, but for various reasons, I cannot get the file from my laptop. (sorry if this image is weird, I cannot get files between the two computers and therefore cannot get a screenshot)

[Edited by Moderator]

Original Title: Disk image "not recognized"

Earlier Mac models

Posted on Sep 9, 2025 7:35 PM

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Answer 1

HWTech

Level 9

68,210 points

Sep 10, 2025 8:27 AM in response to Cyrus_was_taken

If you are only running macOS 10.8 and trying to open that file, then perhaps Apple has changed the compression used which 10.8 doesn't recognize....or perhaps that file is damaged after all there are no browsers for 10.8 which are compatible with today's web standards. Others have reported that macOS 10.11 is the first version of macOS which is still able to access the Apple App Store.

You can try downloading macOS 10.11 or 10.12 using any other computer or OS which is able to access the Internet, then transfer the DMD file to your older Mac.

FYI, here is an Apple article with the links to various macOS installers:

How to download and install macOS - Apple Support

Edit: And please rotate the pictures because it is very difficult & annoying to try reading a sideways or upside picture. It is very easy to rotate a picture on an iPhone/iPad and I'm sure Android devices have similar options:

Crop, rotate, flip, or straighten photos and videos on iPhone - Apple Support

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