Disk Not Ejected Properly "Macintosh HD - Data"

That volume should not be mounted such that you would see that message for the normal data volume. It is not mounted using that name.

Open disk utility and look at the volumes in the list. Do you have more than one Macintosh HD – Data?

If so, when you select one, you should see the home folder icon next to the name in the info pane. The one without the Home folder is an orphan left over from your previous installation. You can remove the orphan by selecting it and click on the remove volume button (-)

I had the same issue right after upgrading to Monterey. I went to System Preferences > Battery > Power Adapter and turned off "Put hard disks to sleep when possible" and I haven't seen it since. This is a MBP that stays plugged in, so you might also want to turn off the same setting under "Battery".

My guess is it's a bug and the system is misinterpreting the sleeping disk. Probably not a problem if the notification doesn't bother you.

Update - turning off "Put hard disks to sleep when possible" seems to have fixed it.

It appears that on Macs that do not offer "Put hard disks to sleep when possible" an alternative workaround is to "Prevent your Mac from automatically sleeping when the display is off". At least this seems to work for me.

Disk Not Ejected Properly - All of a sudden

I was able to work around this bug by checking the "Prevent your Mac from automatically sleeping when the display is off" option.

I have a new iMac 24" M1. Energy Saver does not show the option to put hard disks to sleep on my machine either. Just guessing, but it may be that since the disk is a SSD, it can't be put to sleep in the same sense.

I have the same issue and it started after the Monterey update. Never seen it with BigSur. I have a 27' Desktop with an SSD Not sure what the "Put hard disks to sleep when possible" option does to SSD, but I turned it off to investigate further and will post an update if it returns.

Then I have no idea why that is happening. I have never seen it on Big Sur or Monterey.

Is Macintosh HD - Data mounted in Finder? Do you see it in Go > Computer?

Same exact issue as the OP.

2020 13" MacBook Pro // M1

Monterey 12.0.1

• My wife has the exact same MacBook Pro that I do and she does not have this issue.
• I don't have this issue on my 2013 MacPro.

From my Mac mini (2018):

Mac Mini M1 Monterey 12.01 and not external drive attached

/dev/disk0 (internal):

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      GUID_partition_scheme                         251.0 GB   disk0

   1:             Apple_APFS_ISC ⁨⁩                        524.3 MB   disk0s1

   2:                 Apple_APFS ⁨Container disk3⁩         245.1 GB   disk0s2

   3:        Apple_APFS_Recovery ⁨⁩                        5.4 GB     disk0s3

/dev/disk3 (synthesized):

   #:                       TYPE NAME                    SIZE       IDENTIFIER

   0:      APFS Container Scheme -                      +245.1 GB   disk3

                                 Physical Store disk0s2

   1:                APFS Volume ⁨Macintosh HD⁩            15.7 GB    disk3s1

   2:              APFS Snapshot ⁨com.apple.os.update-...⁩ 15.7 GB    disk3s1s1

   3:                APFS Volume ⁨Preboot⁩                 460.3 MB   disk3s2

   4:                APFS Volume ⁨Recovery⁩                835.8 MB   disk3s3

   5:                APFS Volume ⁨Data⁩                    16.6 GB    disk3s5

   6:                APFS Volume ⁨VM⁩                      20.5 KB    disk3s6

Same here, I started having this same message a couple of days ago. same conditions, right after coming back from sleep

MacBook (Retina, 12-inch, 2017)

Monterey 12.0.1

Same volumes listed as OP as well

Also affecting me (MBP 15" 2018, MacOS 12.0.1)

> diskutil list
/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.3 GB   disk0
   1:                        EFI ⁨EFI⁩                     314.6 MB   disk0s1
   2:                 Apple_APFS ⁨Container disk1⁩         500.0 GB   disk0s2

/dev/disk1 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +500.0 GB   disk1
                                 Physical Store disk0s2
   1:                APFS Volume ⁨Macintosh HD - Data⁩     372.4 GB   disk1s1
   2:                APFS Volume ⁨Preboot⁩                 574.2 MB   disk1s2
   3:                APFS Volume ⁨Recovery⁩                1.1 GB     disk1s3
   4:                APFS Volume ⁨VM⁩                      9.7 GB     disk1s4
   5:                APFS Volume ⁨Rincewind⁩               15.7 GB    disk1s5
   6:              APFS Snapshot ⁨com.apple.os.update-...⁩ 15.7 GB    disk1s5s1

I am also having this issue. It happens a lot. Frequently it shows the error when I first turn on my computer in the morning. Although only once was the drive actually disconnected. This is annoying but it also appears to be non destructive. I hope they fix it soon.