DISK NOT EJECTED PROPERLY keeps popping up Big Sur 11.3.1

Same problem here on iMac Pro with four USB3 hard drives: two 3TB WD in Raid0, a 4TB WD my passport and a 3TB Lacie (used for TimeMachine). I noticed my 2 other ssd drives which use the thunderbolt ports don't get ejected.
The drives get ejected constantly after only few hours of usage. It happens while I'm not using the mac and wake the display. I have set the sleep of the machine and drives to "never". All the drives are directly connected to the computer, no hubs are involved. After they eject, they don't appear in the Disk utility. Only solution is to restart (log out doesn't help).

I have done a SMC and PRAM reset.

I have also wrote Apple feedback, but hope someone provides a solution quicker. I wonder if the problem is apparent in the beta of the next macOS version...

Hi, I have similar issues with 2 of my hard drives, WD passport and elements on my M1 MBA.. These 2 drives work fine with my older MacBook Pro late 2013 on Mojave and my Windows setup but cannot seem to work well on Big Sur..

I've been running a TB2 24tb G-Speed Shuttle XL on my iMac for a few years now. On Mojave I never saw the 'Disk Not Ejected Properly' message. Worked perfectly as expected.

Once I updated to Catalina it started showing up every few days when the computer was asleep. I might see 1 or 2 messages when I logged on in the AM. I updated to Big Sur hoping this bug was resolved and now I see 10-20 of these messages upon awakening the computer. If I eject the drive before putting the computer to sleep it will still result in 10-20 messages.

The only "fix" is to physically disconnect the drive or turn the iMac off. This is not ideal as I am a video editor and backups are scheduled to run at night when I'm not using the machine.

I have spent hours researching this issue and tried every tip/fix I have seen. There are simply no energy settings, cable, reformatting, resetting PRAM etc etc. that resolves the issue. What I have learned is:

1. There are a ton of people that have this issue.
2. The issue is 100% with Mac OS.
3. Seems to be getting worse with each update.
4. Is not on Apple's radar (which seems very un-apple)
5. This is such a bummer that it would be the only subject I would discuss with Tim Apple at a social gathering.

Every time I try to copy a directory from my external USB drive to the SSD on my Mac, the disk ejects and the copy fails. It is 100% reproducible. The USB disk is connected via a USB hub with separate power supply to ensure enough power. I can access the disk, read from it and copy files to it. I use it with Logic to keep my sound library on, and that works fine.

I've just updated to macOS Big Sur 11.5.2 and a bunch of issues started happening:

1. My external disk WD 1TB keeps disconnecting. A pop-up message that says that the disk was not ejected properly when I did nothing to eject or disconnect the disk. It's simply annoying!
2. Checking First Aid on DiskUtility it runs and the result is everything ok... which is not, otherwise the disk would not keep disconnecting!
3. Had to restart the or four times to get the MacBookPro running as expected (as before), and even then, some apps even the finder keeps crashing and becomes irresponsive.
4. At some stage I had to force shutdown "a la Windows" and back to start the system again.

After two forced shutdowns the system recovered, yet, the external disk is being disconnected automatically after this update.

Questions:

1. Will there be an urgent fix, and when?
2. Have Apple been bought by Microsoft? It looks like so or maybe not because my (horrible) Windows machine which serves only to display Google Analytics live tracking has kept working like a mac (weird)!

Comment: in a short period of days, macOS Big Sur has been updated for bug fixes with a frequency that reminds me of Windows in the '90s!! The only thing missing is "the blue screen"!

Hoping to have a stable update that fixes at least this bug of external disks being disconnected.

SMC, PRAM reset, etc.

Formatted drives in several formats, exFAT, APFS, FAT32, Mac OS Extended.

Tried different cables (even thunderbolt certified), different hard drive caddies, tried different ports, tried disconnecting everything except those drives, tried different hard drive brands, restarted several times, ran first aid, reinstalled the OS, etc

Looked all over google about the error 100006 and some random errors trying to erase, partition or reformatting the drive. They get ejected at random, quite often as soon as I plug them they keep getting ejected so I can't even do anything on them at all.

Plugged them into windows and voila! they work just fine!

ADATA SX8200 PRO and Toshiba NVMe M2 drives. Tried several brands for hard drive caddies. Seems like this is a long time error on such a renowned brand, how come this hasn't been fixed? Lots of threads and no solutions! Some manage to get them working, others never do!

This is apparently a universal problem for BigSur.

I hope Apple will solve it soon with an update.

this issue is so bad that it rendered my lacie mobile drive unusable, replaced lacie but lost 4 days of hard work. apple needs some serious spanking

Same here. Seagate 2TB and 4TB on MacBook Pro 2018 running Big Sur 11.6. The 4TB ejects every now and then, but of course always at the wrong moment, like when finishing a complicated video edit. The 2TB disk (my Time Machine disk) is the real PITA, ejecting umpty times a week and in the process screwing up Finder and other apps that are running, only to be fixed by forced reboot. Started with Catalina. Disks are ok when checked in Disk Utility and work fine on older MBP running High Sierra. Apple, please fix ASAP!

It is helpful to know I'm not the only one whose drives are spontaneously ejecting. I've been trying different connections and it is occurring on multiple drives. Mostly USB 3.0. These are all LaCie drives and on at least one if I hookup via Firewire through Thunderbolt, it seems stable. At least one drive has become corrupt due to these issues. I hope Apple can understand that the only thing that changed was their software/hardware. This started for me after 'upgrading' to an iMac M1 and Big Sur. I remember the days when Window machines were this unpredictable, change is the only constant.

Upvote this topic as my Time Machine drive keeps getting ejected. Big Sur 11.6

After dealing with the dreaded "disk not ejected properly" error for months while running Big Sur 11.6 I think i have finally seen the light at the end of the tunnel. I upgraded macOS to Monterey 12.0 this week and my Mac Pro (Late 2013) seems to have stabilized. While the "eject" continued to show up initially after I completed the install, the "eject" errors seem to have disappeared 100%. My setup was related to the use of a Promise Pegasus R6. I tried everything from cable swaps, to firmware updates, to Mac Power Management settings. Now I can only hope that future updates (and I know there will be many) to Monterey will not bring back the dreaded "eject" error.

Hmm this was never a problem for me with Catalina or BigSur - now upgraded to Monterey and just started happening.

Same problem here. Just started happening after upgrading to Monterey. I have an external HGST G-Drive.

Same here. Just updated to Monterey. I have a WD Element and it ejects when I try to access it.