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High Sierra: unable to open HFS disk images: " can't be opened because the original item can't be found"

I upgraded my MacBook Pro to High Sierra a week ago and have been using it without any glitch.


Until today. I have a couple of disk images, and I wanted to open one of them. When I double-click the dmg file in the Finder, an icon appears in the side bar as usual - but when I click on it, I get this error:


"<disk> can't be opened because the original item can't be found"


The disk appears in /Volumes and I can see all the content from the command line. Also from the Finder when I go to /Volumes. The directory structure is correct, but the content is not: files are unreadable.


I then tried creating a new disk image using the disk utility and I get the same effect: the image just created is unusable.


After a bit of googling, I came across a discussion about the new APFS file system: the upgrade converted my SSD from HFS to APFS. But the discussion also says that I need to convert all drives from HFS to APFS. So I did that, and my disk images are now usable again.


This is a bit of a worry: disk utility lets me create disk images in HFS, but then High Sierra is unable to use them ... Bigger worry: any disk image created in HFS cannot be read by High Sierra. And vice versa: obviously any disk image in APFS cannot be read by earlier versions ... So much for upwards compatibility.


I thought that the requirement for migrating to APFS was only for SSDs ? My external drive (the one I use for Time Machine backups) is still in HFS and everything works fine. So it looks like High Sierra is able to use HFS hard drives - which is good. But it has problems with HFS disk images ?


Anyone faced th


What does this mean for disk images used for installing software ?

MacBook Pro, macOS High Sierra (10.13.3)

Posted on Jan 25, 2018 7:40 AM

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Posted on Jan 26, 2018 1:52 AM

You seem to be making assumptions that aren't the case. I'm not sure what's wrong with your install but I can create HFS+ images that can be read. I have multiple external HFS+ drives that can be read. I have FAT32 flash drives that can be read. Time Machine however doesn't not work with APFS drives. It may at some point, but it doesn't now.


Hopefully someone will come along who can help you get your Mac sorted.

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Jan 26, 2018 1:52 AM in response to agodfrin

You seem to be making assumptions that aren't the case. I'm not sure what's wrong with your install but I can create HFS+ images that can be read. I have multiple external HFS+ drives that can be read. I have FAT32 flash drives that can be read. Time Machine however doesn't not work with APFS drives. It may at some point, but it doesn't now.


Hopefully someone will come along who can help you get your Mac sorted.

Jan 26, 2018 1:35 AM in response to agodfrin

I was wrong when I said that external drives work. They actually don't.


The external drive I use for Time Machine backups is now also not recognized. I can see it in /Volumes. It appears on the side bar with a "file" icon. When I click on that, I get again:


“TIME_MACHINE_BACKUP” can’t be opened because the original item can’t be found.

But the biggest trouble is that Time Machine is also unable to use it: it says "Backup Disk Not Available". That is a serious problem.


And I now also have the same issue with a FAT-32 disk image that was working fine. The bottom line is that High Sierra only accepts APFS volumes ...


How can Apple ship something so fundamentally buggy ? After that and the silly iOS 11 release silently slowing down iPhones, I seriously doubt the QA process at Apple.

Jan 26, 2018 2:13 AM in response to CountryGirl56

Maybe I am ...


I just did a full reboot. Now the external drives (including the time machine backup drive) mount correctly and are again usable.


Also I am now able to again open the FAT32, NTFS and HFS+ disk images ...Time Machine works fine again.


That is a relief! I am not sure why a reboot fixed all this. Yesterday I upgraded to 10.13.3 and my disk image / external drives problems started happening after that ...


Thanks for confirming that this is all working for you and is expected to work. I have no idea why a full reboot made a change though. Maybe some process required for mounting non-APFS volumes had crashed ? I will check the logs for any oddity ...

Jan 31, 2018 1:14 PM in response to agodfrin

Thanks agodfrin to clearly state you did a full reboot. After my update to High Sierra 10.13.3 earlier today the same happened to me. USB disks (mem sticks) would not work anymore.

I was under the assumption that after the update and install of the new OS version, the Mac had restarted fully. Not so apparently.

I can go to bed now...


Thanks again

High Sierra: unable to open HFS disk images: " can't be opened because the original item can't be found"

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