OS Monterey unable to open dmg workaround using Terminal

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.

Posted on Feb 19, 2022 12:42 PM

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johngpt5 Author

Level 1

5 points

Posted on Feb 19, 2022 2:09 PM

I'm finding some online comments that suggest that if the dmg which Monterey thinks is corrupted was created some time ago with older OS versions, this problem shows. Apparently a dmg created within one or two OS versions back don't have this problem.

My wrongly thought corrupted dmg had been created on another MBP back in Lion or Yosemite, renamed on this computer in Catalina in order to keep the two files discrete. Big Sur didn't have a problem opening it. But now the problem is solved by using Terminal to open the 'corrupted' dmg, renaming the main folder and using Disk Utility to create a new password protected dmg for it. The newly created dmg opens just as it should in Monterey.

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OS Monterey unable to open dmg workaround using Terminal

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