Since updating to macOS Sierra, my Seagate 1TB Harddrive isn't being read or mounted by my Retina MacBook Pro (2014) ... It appears in Disk Utility but not in Finder or on the Desktop ... In Disk Utility I cannot do anything but format it which I DO NOT want to do .. Any suggestions or help?!
Out of desperation, I tried your solution. Connected the drive to my desktop with a USB extender. IT WORKED!
Thank you.
10.12.4 beta - since updating, external drives do not have correct permissions, and do NOT show up in disk utility!!
A partial solution which at least makes an external HDD usable again.
I have a Rugged Triple FW/USB3 drive which wouldn't mount on Sierra (from 10.12.1 to 10.12.3) on a Mid-2010 MBP. Works perfectly on other machines running Yosemite - tried re-formatting on Yosemite but Sierra still wouldn't mount the drive whether encrypted or not.
Eventually re-formatted as exFAT on Windows 10 whereupon it mounted on Sierra. Then used Disk Utility on Sierra to re-format as Mac OS Extended (Journaled, Encrypted) and all seems well.
Unfortunately had to copy the data to another drive using Yosemite so it's not a solution if you have essential data which you're unable to copy off by other means.
I haven't had any thunderbolt issues on Mac Pro, have had USB mounting problems with HDDs, not flash drives. I have an Apple Thunderbolt Display and when using it's USB ports, I don't have any issues. I'm running 10.12.3, no betas. Maybe if you can run the USB though a thunderbolt hub as a workaround at least. Still should have been fixed months ago.
As of February 2017, a Samsung T3 external SSD is recognized erratically. Sometimes, my MacBook Pro OS X Sierra (10.12.3) recognizes it. Sometimes it doesn't. This is true for both USB ports. I replaced the drive. Same problem with the replacement.
Nothing has been done that might damage the drive, the cable, or the port. For example, with the MacBook powered down, I plug in the drive, start up. No problem. I then shut down and restart. Now the drive is gone. Disk Utility doesn't see it at all. Power down, switch to second USB port, power up. Now the drive is recognized. But at some point, the drive will also disappear from that port.
Repeatable but unpredictable.
This suggests a problem with USB connectivity under Sierra.
can you please help me unlock my iCloud to
I had the same problem with a Western Digital 2TB My Book Studio.
It showed up in disk utility but not in finder.
What I did was right click in the external HD that appears in disk utility and from there you can click show in fnder!
It seems like the partition had a hidden attribute. I was in a hurry so I just grab the HD in finder and add it to my favorites bar in the left side of finder.
I think that I need to research about the hidden attribute but for now I can work and access to my HD.
I hope this works for anyone having the same problem.
Edit:
I also found how to unhide the partition. Just use the chflags mettod.
Open terminal and type:
"chflags nohidden "
With a space at the end and drag and drop the drive from finder to terminal and hit enter.
Use what I explain earlier to get access to your HD in finder using disk utility shorcut
Thank you
roadparc
I had the same problem too, but with a USB 3.0 External Western Digital 3TB HD, My Passport For MAC.
While running a Late 2009 Mac Desktop, with Yosemite 10.10.5, I was attemping to back up with Apple's Time Machine application my Desktop Computer onto my USB 3.0 External Western Digital 3 TB Hard Drive, My Passport For MAC.
The 3 TB HD icon wouldn't show up on either the Finder window or Computer screen, on my Desktop computer, but would show up within the Desktop computer application, Disk Utility, on the left side of it's window. There it would allow me to select Verify and Repair, but once the process ran its course, a window would pop up to say an error has occured: "Couldn't open disk" or "The disk couldn't be unmounted". Now, I know the 3 TB HD was running because I could feel it the rotation of the hard drive and I could see that it's exterior white light was on. So here's how I was able to bring back! Since I had access to an additional computer, with the latest Operating System, Sierra 10.12.3., I plugged the USB 3.0 External Western Digital 3 TB Hard Drive, My Passport For MAC. into a laptop. As some time had passed, 15 to 20 minutes, while I was discussing this issue over the phone with Apple Care, yet before we were able to implement any Apple Care solutions, I opened up the Finder window and sure enough there and on the computer screen, was the 3TB My Passport For Mac! Recap: From my experience, find a newer second computer, even a friend's, who's running the latest operating system. (Allow some time) for the USB 3.0 External Western Digital 3TB HD, My Passport For MAC to be recognized by the computer, a laptop in my case. Check back later with it's Finder window or Computer screen and with some luck, it appears! You're back in business. If not, although I never got around to it, I'm sure Apple Care will have some suggestons. Good Luck and Keep me posted!
Well had the same problem. But found solution!
One of my USB-SATA interfaces does not work. This is correct no way to mount.
But a WD external disk mounted immediately. One other USB-SATA interface I have also mounted immediately.
It seems Sierra does not have all drivers for all USB-SATA devices installed.
Thank you very much nexkulit! Though I had Paragon NTFS on my system already, I downloaded and installed Seagate's version and voila - my drive showed up. A check on volume said it was "dirty" (whatever that means), so I quickly copied the contents back to my iMac HDD and am in the process of doing a secure erase on the stupid thing, right before I throw it in the garbage. I will NEVER buy a Seagate peripheral ever again. This thing has been a nightmare.
Even during the copying it managed to mess things up and reboot my system. Took forever to get the thing mounted again. I hate Seagate with a passion now.
Same here, WD hard drive. Almost shipped it for warrenty repair becaseu I assumed the drive was faulty. Then plugged into a Windows PC and it mounted.
No issues appears again. No work arounds, reboot of the OS donesn't help.
**** !
I have a solution.
Step 1
Open Applications > Terminal (the black/white empty screen where you can write text into it)
Step 2
Run the following command:
diskutil list |awk '/external, physical/,/^$/' | awk ' /[1-9]+[0-9]*:/ { print $3, $6 } 'In my case this outputs:
EFI disk2s1
m disk2s2
Recovery MBAnd the drive which I'm interested in is "m", so my "ID" is disk2s2
Step 3
Run the following command
diskutil mount disk2s2Your drive should now be mounted.
Theory
For the technical explanation of what is going on: The kernel is able to load the usb device, but (I assume) that the system event messaging subsytem fails to handle the new usb storage device detected event for whatever reason (process restart, wrong key name.. what ever.. it's random in nature). therefor kernel sees the device but user space is not, because device is not mounted. The above fixes the loss of the system event notification by doing it manually.
I'm having the same issue. The delay is that the connected disk is running fsck in the background before it shows up, which can take some time. If you open a terminal window, cd to /var/log and "tail -f fsck_hfs.log" (or another if not hfs) you'll see this running.
That said, my fsck never completes successfully, which is an issue that disk disk mounts read-only.
Perfect. Thought I was lost...Elegant solution.
Worked for me! Added a USB extender and *BAM* my Seagate 4TB hard drive showed up.