OS Monterey unable to open dmg workaround using Terminal

johngpt5 wrote:

Yesterday, 18Feb22 I updated from Big Sur to Monterey 12.2.1. Today I double clicked on the password protected dmg I keep on the Desktop in which I keep sensitive data. Searching online I found this is a known bug in Monterey. At the r/MacOS subreddit I found a workaround.

In Terminal type hdiutil attach ~/Desktop/'name of dmg' and press Return. I discovered that it only works if I type the full path. Typing the command and dragging the dmg into Terminal didn't do a thing. When the full path is typed, pressing Return caused Terminal to prompt me for the command. Entering it and pressing Return opened the dmg.

This showed me that my dmg was not corrupted but that the problem lies within Monterey.

Is this a zsh issue

or

applies to bash as well?

Have you added the Terminal.app to Full Disk Access...(?)

>System Preferences>Security & Privacy>Privacy>Full Disk Access

Controlling app access to files in macOS - Apple Support

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

Also, have you tried creating a new password protected disk image and see if it will open normally?

Not that it is necessarily related, but I had problem scanning a large (55GB) disk image with the Disk Utility with the Scan for Restore command. The command kept returning an error in Monterey but worked in Catalina. It seems that the disk image capability isn't being tested as thoroughly as required since disk images are used for backups.

johngpt5 wrote:

No clue.

But thank you for including that screenshot.

I went to the Privacy preference dialog as you've shown and added Terminal.

The command hdiutil attach ~/Desktop/ and dragging the dmg into Terminal still didn't work.

I had to again type the full path for Terminal to prompt me for my password and then open the dmg.

Thanks— very interesting.

johngpt5 wrote:

Searching online I found this is a known bug in Monterey.

Apparently I don't have the "known bug" in Monterey 12.2.1. If I dbl-click on an encrypted .dmg it asks for the password then opens.

johngpt5 wrote:

Was the dmg you dragged into the Terminal command line one that Monterey had said was corrupted, or was it a dmg that Monterey had been able to open?

Well I had none that were corrupted.

johngpt5 wrote:

Typing the command and dragging the dmg into Terminal didn't do a thing.

Just to add, dragging the .dmg into the Terminal after the command works for me.

Well, you didn't actually say Monterey reported the .dmg was corrupted but, I had no "old" .dmg files so I had to create a new one. :)

The .dmg's in question must have been created pre-High Sierra as you mentioned. High Sierra .dmg's work as well.

Just a suggestion. Since you did manage to open the .dmg file, you should create a new .dmg image in Monterey and copy the files over. That way you can just dbl-click on it to open.