.dmg files not opening on Mac OS 12

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Level 1

4 points

.dmg files not opening on Mac OS 12

Having the same problem as Ashley and - whoever commented last. Of course I wanted to add my thought to the same thread, but Apple has helpfully kicked me to the winds here, and I have no idea where this comment will end up. I've had Macs for decades, but if it weren't such a pain to start all over with a PC today, I'd do it in a second. Mac software just keeps devolving and getting buggier. But I digress. Why are .dmg files not opening with the newest operating system (12.3)?

iMac Line (2012 and Later)

Posted on Mar 31, 2022 10:28 AM

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Answer 1

Top-ranking reply

OldToad

Level 2

391 points

Mar 31, 2022 11:41 AM in response to franz248

Give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

NOTE: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following;

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts

• Deletes font caches, kernel cache, and other system cache files

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Answer 2

franz248 Author

Level 1

4 points

Mar 31, 2022 11:06 AM in response to dialabrain

Thanks dailabrain, and at least that's a promising sign. I am so frustrated with Apple these days; after installing 12.3, I have run into this AND learned that my Time Machine is inaccessible and has not backed up since before installing the new OS, and apparently that's definitely related. So for opening your .dmg files, do you have a DiskImageMounter.app app in your Applications menu?

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Answer 3

Mar 31, 2022 11:14 AM in response to franz248

franz248 wrote:

...So for opening your .dmg files, do you have a DiskImageMounter.app app in your Applications menu?

As above, no issues with Monterey here either.

I double-click on the DMG file in Finder and it mounts, if the file system within the DMG is a recognized one.

Double-clicking selects the default app for opening a DMG.

That default app is DiskImageMounter.

You'll want to check if the default app has somehow been changed for DMG files on your particular Mac.

To check that, select the DMG in Finder, and use ⌘-I on the File to summon the information for the DMG.

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Answer 4

franz248 Author

Level 1

4 points

Mar 31, 2022 11:29 AM in response to MrHoffman

Thanks, Mr. Hoffman. I used to be able to open these effortlessly as you describe. Now I double-click and it tries to open, but then nothing happens. The default for opening these is "DiskImageMounter.app" but I have no such app in Applications, nor anywhere that I can tell. And I can't see if I used to have it because I can't go back into my Time Machine prior to when I installed 12.3. I also don't see any such app which I can download. Oy.

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Answer 5

franz248 Author

Level 1

4 points

Mar 31, 2022 11:45 AM in response to dialabrain

Sure enough, it's there! However, it--the app itself--also will not open.

Do you have any idea if this is related to my Time Machine not working? My Time Machine is an external HD connected via a G-Drive Mobile link which shows up in my Finder at the top under my computer. And actually, I am now noticing that an SD disk from my camera is also not showing up there, which is where it usually appears. Are all these "virtual disk" links--if I have that correct--are they all related?

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Answer 6

dialabrain

Level 10

125,189 points

Mar 31, 2022 10:47 AM in response to franz248

No idea what thread you are referring to but, I have 4 installs of Monterey 12.3, and practically open .dmg files on a daily basis so it's certainly not normal not to be able to.

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