Does Monterey Have a Bug with Mounting External Drives & Images?

[Alvin777]

All my other external SSD worked just fine prior to installing Monterey. I can mount and boot my external SSD from recovery without any problems. The drives take an eternity to mount/unmount in Monterey. I'm going to install Big Sur.

Hi. It's now fixed on my side. I upgraded to macOS Ventura (can't wait for Sonoma, I'll most likely install that first on a test partition), fresh install (Time Machine restored but I think manually copy pasting the documents and then reinstalling all the apps would be better and more sure there're less junk from a decade or so of Time Machine restores) but I also upgraded everything to SSD including the Time Machine (one internal NVME SSD). I used FastDMG before to mount .dmg (FastDMG app won't mount the external drives though). Prayers that it'll also work for you. Backup everything first.

 

[Uploading]

Hi. It's now fixed on my side. I upgraded to macOS Ventura (can't wait for Sonoma, I'll most likely install that first on a test partition), fresh install (Time Machine restored but I think manually copy pasting the documents and then reinstalling all the apps would be better and more sure there're less junk from a decade or so of Time Machine restores) but I also upgraded everything to SSD including the Time Machine (one internal NVME SSD). I used FastDMG before to mount .dmg (FastDMG app won't mount the external drives though). Prayers that it'll also work for you. Backup everything first.

Ok I can confirm that Monterey is crap, I just finished installing Big Sur and you're not going to believe this... my external SSD mounted quick with no issues.

 

[Monotremata]

Ok I can confirm that Monterey is crap, I just finished installing Big Sur and you're not going to believe this... my external SSD mounted quick with no issues.

I ran Monterey from first public beta until Ventura's release, and had absolutely no trouble mounting my SSD's in an external USB-C enclosure, along with two USB WD MyBook drives (one is Storage, the other is my Time Machine). That would've put my entire workstation down as those SSDs are where my sample library, and Cubase/Logic Pro projects live. Not a single issue with the old Oyen 2 bay case, and not a single issue with my newer 4 bay OWC case either.

 

[Uploading]

I ran Monterey from first public beta until Ventura's release, and had absolutely no trouble mounting my SSD's in an external USB-C enclosure, along with two USB WD MyBook drives (one is Storage, the other is my Time Machine). That would've put my entire workstation down as those SSDs are where my sample library, and Cubase/Logic Pro projects live. Not a single issue with the old Oyen 2 bay case, and not a single issue with my newer 4 bay OWC case either.

I don't know what it is, it could be because all my externals have HIGH SIERRA on it, but BIG SUR is working great for me.

 

[Ifti]

I have external SSD drives of various capacities, both RAID and non-RAID, all APFS, Thunderbolt and USB-C.
None of them have ever caused me any issues.
MBP16 M1 Max running Monterey.

 

[Uploading]

I have external SSD drives of various capacities, both RAID and non-RAID, all APFS, Thunderbolt and USB-C.
None of them have ever caused me any issues.
MBP16 M1 Max running Monterey.

Mine is a MacBook Pro Retina 13" Early 2015

 

[Alvin777]

I think Apple did something to their external storage drivers in the macOSes after Catalina (Big Sur also suddenly disconnects it, but not as bad as Monterey- it started a little bit w/ Big Sur) that if it's not a fast drive like a hardisk or one of the first to come and slow SSDs from more than 12 years ago, it won't mount it anymore in secret so everybody upgrades to fast SSDs (be it USB, USB-C or Thunderbolt external drive).

macOS is actually dismounting the SSDs in the new M2 Ultra Mac Pros but the difference is it's disconnecting the SSD you stuck in it's internal SSD ports (it's disconnects at times internal drives that expands the built-in storage in the M2 Ultra SOC). It may be the Mac Pro M2 Ultra's hardware too though (design flaw w/ the slots).

May  fix these storage expansion drivers be it internal or external.

 

[kralizec]

Hi, basically I registered just to contribute to this thread, as I experienced this issue for almost a year now, without solution (MBP 15" early 2015). Basically it's some launch agent or daemon that breaks this (and make the booting time very long)

This is what fixed it for me, I did it just 1 hour ago, so it might break again in the future.

Symptoms:
- unable to mount external disks
- unable to mount dmg images (this works using hdiutil, but not from finder)
- connected disks are NOT visible from Disk Utility
Pre-check:
- Reboot your Mac in safe mode and check if the disks are mountable/visible there, if so, good news.

Fix:
Make a backup and remove all the elements in:
- /Library/LaunchAgents
- /Library/LaunchDaemons
- ~/Library/LaunchAgents
- ~/Library/LaunchDaemons
Reboot

That fixed for me (and sped up my boot time)

Maybe it's not the issue for everyone, but this was the first discussion point on these symptoms, so it may be useful to someone.

Let me know how it goes

 

[Cofresi]

Well, this is my story, I have a combination of drives from 500GB to 4TB, five drives in total. Two WD one Seagate and two Iomega(old drives). Anyhow, I was having the same issues with mounting and unmounting drives. I did everything under the sun, the last thing I did was wipe out the drive and install Monterey clean. I have an old Mac Pro late 2013 that can't be upgraded to Ventura so basically this is the end of the road for me in terms of upgrading. Then I mounted each drive one at a time to see if any of the drives could be causing this behavior. Lo and behold, the Seagate 4 TB was causing this behavior, I unmounted the drive and disconnected it from the USB-powered hub and so far none of the other drives have been unmounted. I was able to do TimeMachine and CCC backups to the WD drives without any issues. I don't know if this may be relevant or not but the old drives(Iomega) are still formatted using Mac OS Extended format while the others are formatted APFS. Should I have all the drives formatted with the newest format(APFS) or leave them the way they are right now? I do have to mention that I turned off my screen saver for now and kept my drives from going to sleep. At night, I just turn off the monitors, I will try to put them to sleep later on and see what happens. Is it a possibility that the Seagate power supply was faulty and causing the other drives to get unmounted? I'll keep you informed.

 

[Jeromekem]

Ok folks, I hope this may be of some help.

I'm running a 2019 iMAC and came in at OSX 12.2 with a SSD on board and Sandisk Extreme SSD drives for backups, as well as some WD HDD for backups. first thing I did when upgrading was to make a SuperDuper backup of my OS drive. It failed half way through the copying stage. I'll not bore you with the steps I took in my frustration but nothing worked. I got an error message saying the disk could not be found half way through the copy. It had disappeared from my desktop and had greyed out when viewed in disk utility. It was simply there and then it was not. Tried several times after rebooting and downloading a new copy of SuperDuper. I was using the latest release in any event, which said it worked with Monterey. Reaching out to SuperDuper I had a reply within a few hours and was asked if I was plugging the external drive into a hub? I was. One of those Satachi 'fit under the bottom of the iMAC hobbies. Have used it for years without any problems, so much so I don't so much consider it a hub but an integral part of my iMac. On the advice from SuperDuper I connected directly into the iMac's USB-C port by way of a rear entry. Ran SuperDuper and sat and watched every byte being copied over. It was faultless and worked like a charm. I discovered later that Monterey is not recognising many USB hubs on the market. Apple have apparently known about this since Beta and here we are at 12.2 and still a patch has not been released. For those of you who are finding your external drives not working either connect directly into your main connections or look out for a hub that is known to work. Chances are it is not the drive being rejected, but the hub.

This was actually right. I ran in the same problem. On an old Macbook 2013 (Mojave) everything worked fine, but with an extension (usb-C) cord to my Macbook pro 2019 (Monterey) hickups occured. Indeed changing the extension USB-c cable solved it.

 

[Smarky]

Did anyone find a solution for this?

My SSD failed on my 2015 iMac over the weekend, I bought an external SDD, all is working fine on Monterey EXCEPT I cannot open any disk images or mount any external drives, drives show in system report fine, but not in disk utility.

Same for my SD card.

I can mount DMG files using terminal, just not by double clicking. I've reinstalled and the exact same issue, did not have this issue before and running same OS version.

I thought it might be my firmware as I'm stuck on 173.0 and it seems this model has issues where it doesn't update according to other posts here, but it was working before my internal SSD failed!

Also my bluetooth doesn't work for around 10 minutes after boot, it doesn't turn on and then works fine.

Works fine on earlier MacOS versions, only an issue on. Monterey.

I'm stuck.

 

[Smarky]

Hi, basically I registered just to contribute to this thread, as I experienced this issue for almost a year now, without solution (MBP 15" early 2015). Basically it's some launch agent or daemon that breaks this (and make the booting time very long)

This is what fixed it for me, I did it just 1 hour ago, so it might break again in the future.

Symptoms:
- unable to mount external disks
- unable to mount dmg images (this works using hdiutil, but not from finder)
- connected disks are NOT visible from Disk Utility
Pre-check:
- Reboot your Mac in safe mode and check if the disks are mountable/visible there, if so, good news.

Fix:
Make a backup and remove all the elements in:
- /Library/LaunchAgents
- /Library/LaunchDaemons
- ~/Library/LaunchAgents
- ~/Library/LaunchDaemons
Reboot

That fixed for me (and sped up my boot time)

Maybe it's not the issue for everyone, but this was the first discussion point on these symptoms, so it may be useful to someone.

Let me know how it goes

Exact same issue, how do you delete the files in /system/library/launchdaemons? Seems to not let you, system protection is off.

 

[DeltaMac]

That poster (kralizec) also stated that the external drives would mount in safe boot mode - so possible not helpful to you.
What results do you get from the built-in diagnostics?
Which 2015 iMac do you have? That's the year that Apple moved from the older displays to the Retina displays, so the Late 2015 was available with either display.

New update for Monterey released today, so maybe that can be helpful. I would suggest making a bootable USB installer from that full Monterey system installer. Boot to that USB and let it do a reinstall.

 

[Smarky]

That poster (kralizec) also stated that the external drives would mount in safe boot mode - so possible not helpful to you.
What results do you get from the built-in diagnostics?
Which 2015 iMac do you have? That's the year that Apple moved from the older displays to the Retina displays, so the Late 2015 was available with either display.

New update for Monterey released today, so maybe that can be helpful. I would suggest making a bootable USB installer from that full Monterey system installer. Boot to that USB and let it do a reinstall.

Which Diagnostics? The one with option and d at startup? Yeah everything passes, surprised it didn't flag the lack of an internal drive, but guess it doesn't test that.

I have 17,1 iMac with the 5k display.

What I have found since this post that if I swap out DiskImageMounter from one from an older OS it works for Disk images but not external drives. I also installed core legacy patcher to get up to Somona and that allowed my SD card to be picked up (wasn't in Monterey), but still no external usb drives. I also have an issue with bluetooth taking ten minutes to turn on after boot up, which is on the usb bus.

What I've also discovered is that I can install parallels and run a VM of Monterey which works just fine, I can mount the drives that the host OS doesn't, because although the standard OS won't mount the drives or show them in disk utility they are recognised as usb devices. So I'm wondering if this is some strange security/firmware issue etc.