"Disk Not Ejected Properly" error after El Capitan

Same here. There seem to be some changes as I am niw able to remount my Thunderbolt drive by disconnecting and connecting it whithout a reboot, but that is not what one whould expect of the "best OS X ever".

I have given up on this. If anyone ever finds a solution please post it.

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.

HEY APPLE: I've been a dedicated customer for 22 years. THIS IS UNBELIEVABLY ANNOYING.

Upgrading to 10.11.5 Beta solved this for me.

How does one install 10.11.5 beta?

What are the risks to installing this beta version of OS X and do you think they are they worth it to stop these annoying "Did Not Eject Properly" messages? Those messages seem to have become more frequent since I upgraded to 10.11.4, so I'm open to try something to stop them.

By enrolling in beta versions at this site https://beta.apple.com/sp/betaprogram/

No guarantees of course, as they always say to use it at our own risk, but for me OK so far.

If you wait a little, this problem should disappear in 10.11.5 final version - I would be surprised if they having fixed it in beta will have it back in final version:))

I've upgraded to 10.11.5 and no change. Issue is still there.

I'm also experiencing random disconnects of my Lacie 2Big Thunderbolt 2 RAID after upgrading to 10.11.5.

Unfortunately it isn't fixed for me. Sigh.

Just adding my voice. I haven't had the problem while the macbook is being used, only after a sleep. Both my external working data drive and the drive I use for time machine do the same.

It's not a show stopper, it's just annoying, but I'm also worried I might end up with a corrupt disk, potentially losing loads of work.

Can we have a small update please?! xx

Same issue with brand new iMac 5k and Lacie 2big 8tb.

I daisy chain another lacie thunderbolt drive into it, which oddly DOESN'T disconnect when the 2big does. Spoke with a couple of genius' at the store, and the first suggestion was to make sure "put drives to sleep when possible" wasn't checked in system preferences. Didn't fix my issue, so I'm moving on to a possible spotlight index issue. I'll turn off indexing for external drives and see if this fixes.

If none of this works, I'll return it to the store and exchange for the G-Drive.

NOTE: there is a 14 day return policy, but under Australian Consumer Law this should be covered as the failure falls under unfit for purpose. So don't feel like you're stuck with it simply because it's over 14 days since purchase... as long as you're in Australia. haha.

Hello This is how you can fix this problem... it seems el Capitan comes with over the top security or something. I have a macbook air 2016 with the latest version of El Capitan 10.11.6 and had the same problem with an external hard drive that kept ejecting itself after a minute or so. Fortunately I just fixed this annoying problem... These are the steps:

a) Go to system preferences and uncheck put disk to sleep whenever possible.

b) Download the app: Mountain from App store. (this app used to be free but now it costs about 7dlls). Trust me this app is awesome, it keeps all disks running under control, it is worth it the few bucks.

c) Go to the preferences in the Mountain app and check Prevent Unmount.... This parameter does the job, this app takes care of preventing any of your external hard drives from ejecting itself.

I have the "Disk not ejecting properly" problem with a brand new (4 months old now) iMac. A Lacie 6TB raid drive connected via Thunderbolt ejects after every sleep. I tried all suggestions for 4 weeks and got no relief. Apple bug report techs blamed it on my hard drive, even though the hard drive works just fine on a Macbook pro via USB. When I plug it into the thunderbolt port on the iMac, I get the ejecting problem.

I found Mountain to be extremely buggy. Mountain did not respond to two tech support emails. I deleted it from my computer after a week.

I have not slept my iMac in three months because the drive ejects itself after every sleep. Very disappointed in how this iMac deals with external drives.

Having the same issue on my iMac after installing the new MacOS Sierra. Receive the "Disk Not Ejected Properly" after waking the computer from sleep mode. Looking for a solution.