"Disk Not Ejected Properly" error after EL Capitan goes to sleep and wakes up again.

I did not have this problem before until I upgraded to 10.11.4 on my 2015 15" MBP attached to my TimeMachine drive (USB3 WD 1TB MyPassport). I tried resetting the SMC but it did not help.

The only solution I found was to set computer sleep to never.

I think the workaround (option) that worked for me was -- System Preferences, Security & Privacy, General, Click on Advanced - You might need Admin password at this point. Inside Advanced, I had to make sure Log Out After ___ Minutes is UNCHECKED. I've seen others that were able to set it at a certain time, and they said that worked. For me, I had to UNCHECK the box.

Maybe this will help someone...It's worth a shot!

The problem is not specific to El Capitan. I'm on Yosemite and it happens to me. I have all my drives hidden from Spotlight. I have Time Machine turned off. I have my energy saver preferences all turned off. I have 6 or 7 usb 3.0 drives connected to powered hubs.

Whenever I turn on my program Cubase (a music production program) it disconnects all of my drives, not just one, ALL! and then Cubase crashes, and all of a sudden my mac is super slow.

I'm on a 2013 Mac Pro.

This is absolutely insane! There is no fix for this. I am going to return my Mac Pro and move to Windows because Apple is a terrible company and my work station has become inoperable.

I discovered a solution that works for my Early 2009 Mac Pro with a USB 3.0 dual hd dock whose drives would go to sleep even while disk utility was repairing them.

I came across Keep Drive Spinning.app, a free utility available at http://jon.stovell.info/software/

It allows a user to set specific lengths of time a drive will be kept awake -- a solution that instantly cured the early sleep problem I'd had.

btw, fwiw, the problem occurred in Yosemite as well, but it has never occurred with drives attached via USB 3.0 in Sans Digital enclosures.

Thank you so much Myaka. I will give it a try, hoping for the best!

While I appreciate the suggestions that Myaka and others have made, I'm really appalled that this problem still persists. I really wish Apple would fix this–and soon.

I have an external G-Drive connected to a MacBook Pro Mid 2012 via USB 3.0. It's also exhibiting the same symptoms everyone else is describing. In speaking with G-Technology tech support, I was told this condition doesn't affect every external drive, such as my WD MyPassport. Although G-Technology is familiar with Keep Drive Spinning, they recommended a paid app called Disksomnia. I just reached out to the developer of Disksomnia to see if his app would solve this issue and I await his response. I'll update this thread as soon as I've heard back. Hopefully, we can put this ongoing problem to bed soon. 🙂

Okay, I just tried a tip from Louie at G-Technology. Louie said that if you manually sleep your Mac you will not have a problem with it disconnecting abruptly, which triggers the message, "Disk Not Ejected Properly." I just tried this and it appears he was right. From what I what I was told, this condition ONLY occurs when a Mac goes to sleep on its own. Hopefully, this info is helpful to other users.

The problem happens not only when the mac is asleep. It also happens during data transfer.

Wow! That sounds bad. Thankfully, I haven't experienced that. Did you have this problem prior to upgrading to Mac OS X 10.11.4?

Good question. I've been on 10.11.4 for a long time, but the problem started recently. The keep drive awake app did not work for me either. 😟

Our Disksomnia app was created to keep disks awake while the Mac is running (very useful for anyone dealing with media on external drives to avoid the waiting for spin up). Disksomnia won't fix any effect on disconnects caused by the Mac going to sleep.

Add me to the list of people with the "Did Not Eject Properly" problem.

All Hardware is BRAND NEW out of the box 4 weeks ago:

iMac 27" Retina 5k (Late 2015)

El Capitan 10.11.4

External drives:

1. LaCie 2Big 6T Thunderbolt2 RAID 0

(External Power, Thunderbolt directly into the iMac)

2. GTechnology G-Drive 6T USB 3.0

3. GTechnology G-Drive 4T USB 3.0

(Both on external power, both connected to a USB 3.0 hub, connected to the iMac)

From day one, the LaCie 6T RAID has ejected itself ALMOST every time I wake the iMac up from sleep. Never when it was in use. But when I put the iMac to sleep, and wake it up the next morning, the LaCie 6T RAID is gone from the desktop and I get the error message. If I unplug the Thunderbolt cable from the back of the iMac and plug it back in, the LaCie shows up on the desktop and everything is fine.

The GTechnology G-Drives connected with USB 3.0 have never ejected themselves... Always work perfectly.

I tried getting rid of the thunderbolt cable from the LaCie and connecting it with the optional USB 3.0 cable and continued to receive the error message and ejections.

I called LaCie and spoke to two techs. One suggested it was a drive problem and I was going to initiate a return of the LaCie 2Big but then speaking with a second tech, she suggested trying the drive on a different Mac. All I had was an old MacBook Pro running Snow Leopard... I plugged the LaCie into the MacBook via USB 3 and everything worked perfectly. Repeatedly sleeping and waking the laptop re-mounted the drive every time. So it's not the Drive. It's ElCapitan. The tech mentioned something about "Apple changed how thunderbolt ports work starting with Yosemite... that they were shut off or shut down on sleep and they cut off the external drives." She said that they started getting lots of reports of this happening around that time.

ALSO: I tried the Mountain app to try to ease the hassle of plugging and unplugging cables every time I wake from sleep. When I use Mountain to UNmount the thunderbolt drive before sleep, then sleep the iMac, Mountain is supposed to REmount the Lacie thunderbolt drive on waking... but the drive just disappears. Even Mountain can't find it on waking. At least I'm not getting the error message, but I still need to physically unplug the thunderbolt cable and replug the cable for the drive to be seen and remount... every time I sleep my mac.

I just found this suggestion on MacRumors:

http://forums.macrumors.com/threads/disk-not-ejected-properly-error-after-el-cap itan-goes-to-sleep.1928103/page-2

USB3 via a PCi board in MacPro can be dodgy when the computer sleeps. My experience is the power to the board is cut when the computer sleeps and while the board will power back up when the machine wakes, it does not always wake up the drive, which then "disappears". Here is the solution I found: I connected the drive to a powered USB3 hub that is connected to the USB3 board in the computer. The hub power apparently is enough to allow the computer to sleep and allow the drive to wake when the computer wakes. The native USB 2.0 ports appear to handle sleep differently.

This is an interesting idea. Not sure it will work on a MBP, but I'm trying it now.