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

It is possible that the problem is related to your LaCie drive in your case, but I think this wide-spread problem is a System problem that Apple simply does not know how to fix. Unfortunately, I don't know how to fix it either. I've tried almost all the "fixes" posted in this and other Mac forums. The only thing that actually works for me is to prevent the Mac from going to sleep (System Preferences/Energy Saver/Computer Sleep).

Some observations that may or may not help:

I first encountered this problem with Mavericks on my 2013 MacBook Air, which has a single Toshiba 1TB portable hard drive connected to one of the MBair USB 2.0 ports. It went away after upgrading to Yosemite.

Meanwhile all was well with my 2011 iMac until I installed El Capitan in late 2015. It started happening sporadically, and none of the El Capitan updates so far (through 10.11.5) have fixed it. A "clean" reinstall of El Capitan also did not fix it.

When it occurs, I get notification banners for all four of my external hard drives. Three of them are Western Digital and one is a LaCie. One of the Western Digitals is plugged directly into a USB 2.0 port on the iMac and the other drives are all connected through a powered USB 2.0 hub. I also lose the EyeTV Hybrid analog/digital Cable TV tuner that is plugged into the powered hub. It reboots itself just as it does when the computer has been restarted. This suggests to me that maybe this is more of a general OS-X USB management problem than a specific issue with hard drives.

I had this issue on my 2011Imac 27", The concern only started when I update to El Capitan,, I run 3 external hard drives and Time machine, have tried every method I could think of

I found that the issue was fine with all my USB drives disconnected then I reconnected 1 at a time and all was ok until I brought back in my USB Powered hub (TP Link) this only applied to one drive as there isn't enough sockets as std, I then read up on hubs and purchased a Hoo Too hub (this reduced my Disk Not Ejected warnings by 90%) and is still this way 6 months later.

I recently had an issue with a corruption in my system and eventually had to reformat CMD & R and then manually reinstalled my docs and photos etc as Time Machine was corrupted this left me with a fresh install of El capitan accurate to that day , I then started to think this may have fixed the disc error in full so left it in sleep overnight and woke up the next morning with the same warning and thats after a reinstall and a clean time machine , the only thing I can feed you guys is the Hootoo hub improved things although I dont think it will help everybody

Good luck

Alan

I did a clean install of OSX on my iMac and it did make a difference. I've since sold that and now have a brand new 5k iMac and it still happens but only very occasionally now, and still with my LaCie 2Big thunderbolt drive directly connected. My USB 3 RAID boxes are without any issues.

Exactly the same issue. What is wrong with Apple, this does not happen on my yosemite mac desktops. Every morning for the last month and a half, brand new el capitan mac desktop, "Disk didn't eject properly." WHY!!!

Upgraded to 10.11.6 and now I have all three of my external drives ejecting.

For 4 months, It was just my LaCie 2Big 6TB thunderbolt drive and only when waking from sleep.

Since upgrading to 10.11.6, my other two GTechnology GForce drives are both ejecting themselves. So far it only has happened during backups... I have one 6TB GForce drive (USB 3.0) set to backup my External LaCie 6TB drive via Time machine. So every hour, it tries to run Time machine and every time, in the middle of the backup, the GForce drive ejects spontaneously. Right in the middle of the backup.

Meanwhile... I have the other GForce (USB 3.0) Drive 4TB drive set to backup my iMac internal 2TB drive via Carbon Copy Cloner. This task runs every morning, and every time, the GForce drive ejects itself in the middle of the backup.

For 4 months, these USB 3.0 drives have been running backups without issue. Since 10.11.6 a week ago, these things are ejecting at each backup.

So three drives, all different, are all ejecting now right i the middle of tasks. It can't be the drives. This is all since the 10.11.6 upgrade.

I'm about to carry all this stuff into the apple store and talk to a genius. SO EFFING FRUSTRATING.

Here's my story,

My Internal 2TB Seagate 7200 RPM drive failed after a got the same Improper Disk Not Ejected Properly Error message. Now my disk won't show up anywhere. Not in Disk Utility, Disk Warrior, TechToo Pro 11. It's supposedly dead.

Then a few hours later, I'm using the USB Flash Drive of Disk Warrior to check some things, and right in front of me the USB Disk ejects with the same "Disk Not Ejected Properly", and NOW that disk is useless and doesn't show up anywhere. Unbelievable!

Below is a screen shot of what I found in the console messages for my Internal Hard Drive?

My System:

OS X 10.11.6 El Capitan

MacPro (Early 2008) 2 x 2.8 GHz Quad-Core Xeon

Memory 32 GB RAM

Graphics Card AMD Radeon HD 7950 3072 MB

Any other thoughts?

Thanks in advance everyone!

And here is the error msg for the Disk Warrior Drive that supposedly unmounted all on it's own. So now I have both USB drives and Internal drives ejecting. wow this is something else.

El Capitan 10.11.6, same problem. Started after updating to El Crapitan. Mac Pro trash can with Thunderbolt Pegasus R6 RAID

2009 Mac Pro with third-party USB 3.0 card, using 10.11.6 -- Adding to the (strange) collection of issues: I purchased a Unitek drive dock that connects via USB 3.0 and does not spontaneously unmount drives loaded in it. My SansDigital USB 3.0 enclosures continue to work flawlessly. My Xiaobi dual drive dock continues to unmount drives spontaneously. The seller of the Xiaobi on Amazon read my review, contacted me, and believes I have a bad unit. He is sending a new one. I'm hoping that will fix things at my end. It does seem to indicate that the issue may be with how well the SATA to USB 3.0 conversion is handled -- by the external enclosure and its synergy with Apple's hardware and software.

I miss Steve Jobs, Apple has severely declined in several ways since his passing. I have this very same issue with WD Passport hard drives where it NEVER happened before switching to El Capitan. Sad, very sad.

Received new dual drive dock (Xiaobi) from alert Amazon seller (who read my Amazon review about ejects and contacted me with replacement offer); spontaneous ejects have ended. Formerly affected drives now sleep without ejecting under 10.11.6. USB 3.0 is working with SansDigital, Unitek, Xiaobi enclosures and third party PCIe USB 3.0 card on my early 2009 Mac Pro.

All is well with the world.

If my experience can be generalized, those of you experiencing sudden ejects might care to contact your drive enclosure supplier to see if they have had issues with faulty SATA to USB 3.0 or Thunderbolt hardware.

Unprintable. After a day of flawless performance, I woke this morning to "Disk Not Ejected Properly" alerts for two drives in my replacement dual drive dock. Thought I'd beaten this monster. Not so.

So sorry to hear that, yes, it's a daily morning grind, seems we're all stuck with zero help.

Changed Energy Saver prefs setting for Computer sleep to "Never." Spontaneous ejects stopped. "Put hard disks to sleep when possible" remains checked but, strangely, does not eject drives, which can clearly be heard to spin down when not in use. So it seems that I, at least, have a computer sleep issue.

I feel as if I'm trapped in a Socratic dialogue going in circles -- one of Dante's circles. With computer set to never sleep, two drives in my Xiaobi dock ejected on their own, but only once today, and not for many hours now. Were I the pulling-hair-out type, I'd be bald.