With Monterey update, can't see certain hard drives

What is the exact model of the laptop? You can get this information by clicking the Apple menu and selecting "About This Mac".

What file system is on those drives?

If you are using the manufacturer's proprietary software to manage those drives, then that software may not be compatible with Monterey. See if the drive manufacturer has an updated version of their app and if there is no update, then you will need to wait until the drive manufacturer updates their app for use with Monterey.

Within Disk Utility click on "View" and select "Show All Devices" so that the physical drives appear on the left pane of Disk Utility. See if the physical drives appears when you connect the problematic G-drives. If the physical drives appear, then the drives are being seen, but it is a file system or partition issue.

Also make sure to connect the drives directly to the laptop without any hubs, docks, or adapters (unless the adapter is necessary to convert the USB-C to USB-A) since these items can sometimes cause problems. If the drive is connected directly to the laptop, then sometimes using a powered USB3 hub from a respected manufacturer can help alleviate drive problems.

Are the external drive encrypted?

Try rebooting the laptop since Finder & Disk Utility can get into a persistent weird and confused state at times if something unexpected happens and only a reboot will resolve the problem (at least until the event is triggered again).

Try a PRAM Reset and it never hurts to do an SMC Reset (follow the instructions for the T2 Mac).

Try accessing these drives while booted into Safe Mode.

Check to see which chipset your various G-Drives use by checking in the System Profiler (under Storage, or USB, or Thunderbolt -- not sure which is best). You can access the System Profiler by Option-clicking the Apple menu and selecting the first item (the Option key toggles the first item on the menu and perhaps other menu items). Maybe Monterey has a problem with certain USB chipsets used in external drives. I know Big Sur and/or M1 Macs had these types of compatibility issues last year as there were lots of posts here on these forums, but I've never really seen any in-depth article or analysis of the issue except that the JMicron USB chipset was fingered to have problems -- perhaps some other ones as well.

Use the Terminal app to try to manually mount the external drive to see if it may provide an actual error message. You will need to correct drive identifier for the volume on the external drive. You can get this by using Disk Utility. Using your screenshot as an example the drive identifier is "disk2s2", you must verify the drive identifier each time you mount the drive because the identifier will likely change. Here is the sample command where I use a generic drive identifier of "diskX" so make sure to replace "diskX" in my example with the correct drive identifier such as "disk2s2":

diskutil  mount readOnly  diskX

If this fails, then it may be interesting to see the output of the following command when run from Monterey and from the other MBPro where the drives are working. It is best to disconnect all other external drives so that only the information about the G-Drive is displayed.

diskutil  list  external

Is the data on these G-Drives backed up somewhere else? You should always have frequent & regular backups of the computer as well as any external media which contains important & unique data.

pdtnyc Said:

"With Monterey update, can't see certain hard drives After updating this morning, I can't see certain G-drive hard drives on my MacBook pro. Some that I formatted over a year ago are fine. The two new most recent ones won't appear. I have checked that the finder show all hard drives. Disk utility doesn't seem them either. However, when I plug them into another MacBook pro that hasn't been upgraded they appear in the finder. What should I do? Thanks!"

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What Comes to Mind:

A. Reformat the drive, making it APFS.

IMPORTANT: Export the data first using a Mac with a macOS of Mojave or before.

B. On each volume click the "First Aid" button.

Screenshot:

What happens if you click "Mount" in the menu at the top of the screen, does it mount?

Every so often a major OS update doesn't "remember" that other drives were mounted before and so won't mount them after the upgrade until you mount them manually for the first time.

Same issue here, none of my drives are mounting and/or disconnect and connect sporadically. Going to try reformatting an empty drive see if that fixes things. But fairly unacceptable that these computers would ship with a bug like this – none of my other macs have any issues, just for some reason this one?

None of my machines have any issues with external drives, so the next task is to figure out what’s different here.

People have been testing with these releases for months now, so if it was an obvious bug it would have been found and squashed by now.

But the bane of any computer maker’s existence is that this may be the first time your particular combination has been tried, and it may yet be an issue with your device.

The key is to be methodical about sorting it out.

HWTech wrote:

Use the Terminal app to try to manually mount the external drive to see if it may provide an actual error message. You will need to correct drive identifier for the volume on the external drive. You can get this by using Disk Utility. Using your screenshot as an example the drive identifier is "disk2s2", you must verify the drive identifier each time you mount the drive because the identifier will likely change. Here is the sample command where I use a generic drive identifier of "diskX" so make sure to replace "diskX" in my example with the correct drive identifier such as "disk2s2":

diskutil mount readOnly diskX

Oops, the command I suggested for mounting the volume is slightly incomplete as I forgot to include the "s2" part of the identifier which tells the command to mount the APFS volume such as "Nassau 22". The command should look like the following example, but replace the "X" in "diskXs2" with the proper identifier (at the time the screenshot was taken it would be "disk2s2".

diskutil  mount readOnly  diskXs2

If the drive identifier is "disk2s2" as shown in the screenshot, the command becomes:

diskutil  mount readOnly  disk2s2

Note to @TheLittles and @Dogcow-Moof, I suggested the command line method of mounting as it is more likely to produce an error message if the mounting process fails plus the command is mounting the volume as Read-Only which should make it more likely for the command to work in case there is a file system issue. I've found recent versions of Disk Utility may not even give an error message and may just silently fail making the user wonder if the "mount" button even activated.

pdtnyc Said:

"With Monterey update, can't see certain hard drives: After updating this morning, I can't see certain G-drive hard drives on my MacBook pro.[...]"

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Tried Recovery Mode?:

Try mounting these in Recovery Mode. [Hold Down: command + R upon boot]. Then, go to Disk Utility, seeing if you can mount the drive(s).

pdtnyc Said:

"Thanks. Disk Utility returns an error message that says it can't mount the disk."

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You are welcome.

A. Verify the Connection:

Enter this code in Terminal:

diskutil list

Are these seen?

B. Single Out this User:

Try creating a new administrator user. See if this then works. If so, then it is an issue pertaining to your current user. If not, then it is an issue pertaining to the macOS.

pdtnyc wrote:

Thanks. I will end up pulling data from the hard drives using another computer. Will try the command line instructions tomorrow. What’s puzzling to me is that older G-Drives have no problem mounting to this computer. I would expect the exact opposite result.

The newer drives are likely using a newer chipset or perhaps even a completely different brand of chipset from the older drives. Some chipsets tend to be more reliable and more supported than others. Plus there is a chance the newer drives are using a different block/allocation size than the older drives which can easily occur with larger drives. Perhaps the newer drives are also utilizing some other new technology which is not completely compatible with some Mac hardware or perhaps only incompatible with Monterey (hopefully just temporary).

Years ago I ordered an external drive enclosure of a brand I had never used before and discovered it would not work properly on a Mac although it seemed to work fine on a standard Windows PC. Macs can sometimes be very picky about third party hardware.

Most likely you will need to contact the G-Drive manufacturer for assistance and possibly alert them to a possible compatibility issue with Monterey. You may want to check the G-Drive website to see if the manufacturer has posted any information about compatibility issues with Monterey.

I have the exact same problem. I spent hours online last night and on the phone this morning with someone from Apple, very nice people but no joy with the hard drives. All four of my drives are no more than 2 years old and none of them show up. They do show up in Safe mode and I have tried the reset SMC multiple times. Very frustrating. Now looking at buying one new large hard drive and then having someone pull all the data over. I have both WD and G-Drive drives. The person who was helping me said he'll call me back on Tuesday and he's hoping he can find something out. I've looked all over the internet to see if WD has anything out but they have made no mention of support for Mac Monterey. All of my computer work is done from the drives, lover 100,000 photos on them. So unexpected!

FYI. In the spirit of not giving up I disconnected a wacom tablet from the computer, mostly because I don't use it and I was trying to simplify my desktop, I had shut the computer down...and magically when I rebooted the mac everything was back in its right place, all my hard drives lined up where they should be....so very happy about that! The wacom was connected via a hub. I had actually plugged a small disk into the hub to see if that would work and it did show up, too, but the reason seemed to be the wacom tablet being plugged into the hub. Just an FYI for something else to try...I'm fixed and happy!