Sonoma fails to open .dmg

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Level 6

19,574 points

Sonoma fails to open .dmg

macOS 14.0 Sonoma fails to open some .dmg with an error "The disk image couldn't be opened. The operation couldn't be completed. Permission denied".

The same .dmg opens OK in macOS 13.6 Ventura.

Most .dmg open OK in Sonoma but I noticed that many .dmg with a license agreement pop-up have the same problem. Such as:

GraphicConverter, TinkerTool, DMG Canvas:

https://www.lemkesoft.de/en/products/graphicconverter/download

http://www.bresink.com/osx/0TinkerTool/download.php

https://www.araelium.com/dmgcanvas

Also Spotify installer seems to fail with a similar error "An error occurred while trying to mount the downloaded Spotify disk image".

This error is not widely reported so I suspect it might be caused by my setup or maybe my oldish Mac mini 2018.

-> Question: Do others with a similar setup experience this?

This is a clean macOS 14.0 Sonoma install to an external disk. No 3rd party virus apps, "cleaning", "optimizing", "speed-up" apps, or VPN.

I have unsuccessfully tried to fix this by:

Safe-boot

Disable macOS internal Firewall

Right-click > Open .dmg

In another new user account

Safari download location from ~Desktop to ~Downloads

Safari "Open safe files after downloading" from OFF to ON

Download with Firefox instead Safari

Dirty macOS 13.6 -> 14.0 upgrade on an external disk

It seems the quarantine flag is no properly cleared. A workaround that fixes this is:

xattr -d com.apple.quarantine file.dmg

But I'd rather let macOS more gracefully automatically handle this.

Mac mini

Posted on Sep 28, 2023 6:15 AM

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Answer 1

Top-ranking reply

Matti Haveri Author

Level 6

19,574 points

Jan 9, 2024 9:41 AM in response to BillyC69_Scotland

This was fixed in macOS Sonoma 14.1, and it still works for me in macOS 14.2.1. Do you have an URL for some offending .dmg?

The old workaround was to give "DiskImageMounter" Full Disk Access in the Privacy & Security System Settings.

/System/Library/CoreServices/DiskImageMounter

Or clear the quarantine flag with:

xattr -d com.apple.quarantine file.dmg

But I have not needed those workarounds.

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Answer 2

HWTech

Level 9

68,186 points

Oct 12, 2023 10:43 AM in response to Matti Haveri

I just encountered this issue with a clean install of macOS 14.0 Sonoma while trying to mount the .dmg for Vivaldi (I saw the EULA & accepted it, but refused to mount the image). You need to give "DiskImageMounter" Full Disk Access in the Security & Privacy System Settings. You will find "DiskImageMounter" at:

/System/Library/CoreServices/DiskImageMounter

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Answer 3

Matti Haveri Author

Level 6

19,574 points

Oct 2, 2023 6:27 AM in response to Matti Haveri

"Michael Tsai from DropDMG: There’s a bug in macOS 14.0 that can cause this error. [...] macOS 14.1 (beta), which seems to fix this bug."

https://forum.c-command.com/t/dmgs-with-license-agreement-fail-to-mount-onto-some-sonoma-installations/15494

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Answer 4

Matti Haveri Author

Level 6

19,574 points

Oct 26, 2023 12:33 AM in response to Seth Willits

This was fixed in macOS Sonoma 14.1.

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Answer 5

Matti Haveri Author

Level 6

19,574 points

Oct 13, 2023 1:28 AM in response to HWTech

> give "DiskImageMounter" Full Disk Access

Thanks, that fixes it for .dmg with a license agreement pop-up (GraphicConverter, TinkerTool, DMG Canvas, Vivaldi, EazyDraw etc). But Spotify installer still fails with a similar error. I hope Sonoma update will fix this.

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Answer 6

Matti Haveri Author

Level 6

19,574 points

Oct 18, 2023 2:01 AM in response to HWTech

> giving the Spotify installer "Full Disk Access"

That did the trick, thanks.

Spotify installer does not prompt for Full Disk Access so the user must do it manually. Otherwise there is this error message that only prompts to re-download the same installer:

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Answer 7

Oct 25, 2023 9:34 PM in response to Matti Haveri

Developer of DMG Canvas here 👋🏼 — It's not an issue with developers not having "updated" Sonoma disk images available; There is no such thing. Any disk image is effectively future compatible on all versions of macOS long into the future. (You can still open disk images made way back in early OS X 10.4 days, for example.)

Something in macOS itself changed, and it's only happening for *some* installations. All disk images I test work on my fresh installs of Sonoma, yet for other people some disk images fail with the permissions error. There's definitely the possibility of it being a bug in macOS at some level (missing permissions, or in the mounting process itself), but it's not clear where or what leads to it.

If anyone finds any pattern to the permission denial, I'm certainly interested in tracking it down.

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Answer 8

essej

Level 1

0 points

Jan 2, 2024 1:56 PM in response to Matti Haveri

I've just had a user report this issue on a DMG (with a license agreement popup) I created who is running Sonoma 14.2.1, so it's possible the bug has crept back in, if they actually fixed it at all...

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Answer 9

Sep 28, 2023 6:33 AM in response to Matti Haveri

This generally means that that dmg image is not compatible with Sonora. You'd have to contact the vendors of each application not opening to find out if they have updated versions or what their intentions are for supporting Sonora. This is just ONE possibility of many.

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Answer 10

Matti Haveri Author

Level 6

19,574 points

Sep 28, 2023 6:41 AM in response to Randall_2023

> contact the vendors

CraphicConverter support replied that "Mount works perfectly and they see no issues". Those other sites I collected from similar very few other oldish Sonoma beta era error reports -- I do not use those products (I did not try to reach Spotify "support").

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Answer 11

HWTech

Level 9

68,186 points

Oct 17, 2023 5:56 PM in response to Matti Haveri

Matti Haveri wrote:

But Spotify installer still fails with a similar error. I hope Sonoma update will fix this.

Have you tried giving the Spotify installer "Full Disk Access"? If Apple got their own stuff wrong, then it wouldn't be surprising third party apps may not be compatible either.

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Answer 12

Oct 12, 2023 4:47 PM in response to Matti Haveri

When I downloaded a .dmg file, then drag it to the Applications Folder, it just copied the same .dmg file to the applications folder without running any script, so the application associated with the .dmg did not run. This use to work on OS CATALINA, but does not work on OS SONOMA.

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