Time Machine failures/external drive keeps disconnecting with Ventura 13.4

This problem seems to relate to ANY SSD Drive, I have 3 different models of SSD external drives, and they are forever disconnecting under 13.4.1 venture on my Mac mini and older Mac. It is not related to the SSD it is a bug in the operating system.

It never happened before I upgraded to 13.4 it worked fine on the same set-up.

So you are not alone with this and it would be good if Apple fixed this bug.

My Time Machine external SSD kept disconnecting and causing kernel panics on my Mac Mini M2 with Ventura and eventually the volume wouldn't show up.

The NVME M.2 card (a WD SN850x) was still under warranty and they sent me a brand new one.

I have two of the same external drives, one for the Time Machine, and I boot off another WD SN850x in an Acasis enclosure (same model: TBU405).

So I was so excited to have figured out that it was a bad hard drive, and formatted the brand new replacement WD SN850x, and started the backup. Next time I came to my computer, the Time Machine backup had failed because the Time Machine drive again had disconnected itself.

So my brand new Mini M2 Pro is constantly needing reboots: whenever the Time Machine drive is connected it is about a 50/50 chance that I try to wake the Mac from sleeping and it has to reboot because of some Kernel Panic, or I have to reboot the thing to re-connect the Time Machine if I want to have backups.

To recreate the problem: get two identical 40gbps Acasis enclosures, two 4tb SSD NVME cards, boot off of one of the drives and put Time Machine on the other. I have maybe 1.5tb of data to back up. Both of my external drives are APFS Encrypted format.

I swapped the WD NVME cards between the Acasis enclosures to be sure it was the card and not the enclosures. I bought many Thunderbolt 4 cables and tried them all.

NOTE: I just upgraded to Sonoma and was running Time Machine while typing the above. Since my first attempted Time Machine backup failed on Ventura earlier today (on a brand new SSD), I upgraded to Sonoma. Erased and formatted my external SSD Time Machine to APFS Encrypted, started a Time Machine backup, and got to about 75% before the SSD disconnected itself. So now my first Time Machine backup on a brand new WD 4tb SN850x freshly formatted card has failed a 2nd time.

"* Unless you're using a network backup disk, make sure that your backup disk is connected directly to your Mac, not through a USB hub or other device."

If Apple didn't keep changing ports on its macs all the time, we would not have to use "other devices" to connect our hard drives to them. This morning I had dozens of "disk not ejected properly notices". One of my two drives (the Time Machine one) also died in the process. Sigh.

Hello jessd6,

Thanks for posting in the Apple Support Communities. We're happy to look into this with you.

To start working towards a solution for this issue, we suggest the steps provided in article, If you can't back up or restore your Mac using Time Machine - Apple Support. We've included the actions you'll want to follow below.

* Make sure that you're using a backup disk supported by Time Machine.

* Unless you're using a network backup disk, make sure that your backup disk is connected directly to your Mac, not through a USB hub or other device.

* If your backup disk is connected directly to your Mac, use Disk Utility to repair the disk.

* If you're using a network backup disk, make sure that the network connection is good and your Mac is connected to the same network as the backup disk. If you completed a previous backup successfully, verify that backup: Press and hold the Option key while choosing Verify Backups from the Time Machine menu in the menu bar.

* Make sure that the firmware of your backup disk is up to date. Check with the manufacturer of the backup disk for details.

* If no other solutions work, start over: Erase your backup disk, then use Time Machine to select it as your backup disk again. 

Keep us posted on how it goes, and which step correct the issue you're facing. If you find none of the actions help, we'll be happy to continue researching possible solutions.

Best regards.

the timing of this screams os issues. see time machine keeps ejecting my backup dis… - Apple Community, which deals w/ hdd backup drives. glad we saw this before we purchased an expensive ssd backup drive

Similar problem with similar setup. Mac mini M2 Pro on Sonoma 14. Acasis TBU405. Tried with Fury Renegade and WD Green, both 2TB NVMe. Lucky that mine just disconnect occasionally like maybe once a week or fortnight. Almost never turn off my mac. Perhaps a reboot every few months. And I have two NVMe connected to my mac via Thunderbolt 4, one for daily use and one for time machine - both of which are placed on always-on cooling pad. My daily one is estimated at 35 degree celcius (Macs Fan Control) at the time of writing and the time machine one (which cannot be shown by god knows why) is likely even lower as it was just hanging around doing nothing atm. What I'm trying to say is the heat seems not an issue here in my case. Considering to buy a WD Red NVMe as it seems dedicated to always-on and higher temperature environment. Would be great to know what the true solution is.

First time trying to actually setup Time Machine for my new Mac Studio. Usually just use Carbon Copy Cloner, but thought I would give Time Machine a shot this go around. Bought a new external SSD, formatted it, got things going with Time Machine, then received the "Disk Not Ejected Properly" notification. Tried resetting the computer, using different thunderbolt and USB ports, tried reformatting the disk again...and still the same issue. "Disk Not Ejected Properly"

Running on OS 14.2.1. Would love to know if there is any update on getting a fix for this issue!

This issue drove me nuts for awhile.

Hopefully this helps some of you all.

Avoid putting hard disks to sleep.

Check your battery/energy settings to never put hard disks to sleep.

Once I adjusted this to Never, finally my time machine backups were able to finish again without disconnecting.