Secure partition .dmg won't open after upgrade to Sonoma

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Level 1

21 points

Secure partition .dmg won't open after upgrade to Sonoma

I recently upgraded my macOS to Sonoma and now a secure disk image I had created for my taxes will not open. When I click on the .dmg file I get an error that says, "The disk image couldn't be opened. The operation couldn't be completed. Input/output error." I have tried fixing it with first aid in disk utility. I have tried restoring from Time Machine. I keep getting the same error and the image will not mount. This is a big issue for me. How can I recover the information on this disk image???

System details:

2019 27" iMac 3Ghz i5

40GB 2667 DDR4

macOS Sonoma version 14.0

iMac, OS X 10.11

Posted on Oct 13, 2023 11:03 AM

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Answer 1

Top-ranking reply

HWTech

Level 9

69,338 points

Oct 16, 2023 10:26 AM in response to nome_man

Try giving DiskImageMounter Full Disk Access. In the "Security & Privacy" section of System Preferences you need to add "/System/Library/CoreServices/DiskImageMounter" to "Full Disk Access".

Don't know if that will address your problem, but it allowed me to open .dmg files within Sonoma.

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Answer 2

Oct 13, 2023 10:47 PM in response to nome_man

I'd install the previous known-good macOS version to an external disk and see if that works.

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Answer 3

rnmig

Level 1

8 points

Dec 21, 2023 12:24 PM in response to nome_man

Trying to open a pre-Sonoma .dmg file from Sonoma, I get a message that "The disk image couldn't be opened Failed to mount filesystems". How do I access pre-Sonoma .dmg files? This was not mentioned as a feature of Sonoma, is it intentional?

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