TS1550 "Partition failed - couldn't unmount disk"? what next?

While trying to "fix" TimeMachine backup "failing" -- researched "Help" and followed the "disk utility" /partition=1/GUID/apply & got above message -- have no idea what to try next. Time Machine has periodically been popping up with "Failed" for about 2 weeks now. This happened once before (maybe 1 year or 18 months ago), but the aforementioned "fix" worked that time? Where do I go now?

Have you looked through Pondini's extensive TM help site?
http://Pondini.org/TM/FAQ.html
Can't imaging something not being covered there.

Similar Messages

Partition Failed -- Could not unmount disk

I partitioned my external hard drive into two parts. Now I want to change it back to one partition (500 gb).
I backed up all the data.
When I use disk utility and try to re-partition to create one partition from the two existing partitions, I get the error message:
Partition failed
Could not unmount disk.
What am I doing wrong??
THANKS.

Sean M wrote:
I partitioned my external hard drive into two parts. Now I want to change it back to one partition (500 gb).
I backed up all the data.
When I use disk utility and try to re-partition to create one partition from the two existing partitions, I get the error message:
Partition failed
Could not unmount disk.
What are you booting from Sean ?
You could always startup with the external Off, runn DU then turn external ON.. and try.

HT4718 i need to install a fresh copy of OS X onto my macbook pro 13. i did erase the old partition "macintosh hd" & now when i am trying to create a new partition, it shows "partition failed..couldnt unmount disk"...pls help !!

i need to install a fresh copy of OS X onto my macbook pro 13. i did erase the old partition "macintosh hd" & now when i am trying to create a new partition, it shows "partition failed..couldnt unmount disk"...pls help !!

First of all, I have to ask, why to you "need" to install a fresh copy of OSX?
This may mean that your hard drive is failing, so hopefully you have a backup.
I'm assuming you were in your recovery partition when you did this.
I would, from the recovery partition, repair your hard drive and permissions.
When to Run First Aid in Mountain Lion's Disk Utility - For Dummies
And then try to create the partition again.
If that doesn't work, you have a few options:
Try a third party utility like DiskWarrior or TechTool which may be able to repair your hard drive:
DiskWarrior 4 - The Disk Utility for Mac Disk Repair, Mac Directory Repair, Mac Disk Recovery, Mac Data Recovery or Techtool Pro 7
Try internet recovery, perhaps erase the entire hard drive and reinstall ML.
If nothing else works, then I'd replace the HD and start over.

Partition error. couldn't unmount disk

I new buy mac mini 2012. I have osx mountain lion.
When I create a partition get error "Partition Error". "Couldn't unmount disk"
I haven't OS now. Because I removed its.
I can't create partition under 500 GB HDD.
And I'cant see Recover HD.
My disk Utility Screen:
When I create partition I get below error pop-up message.
When I browse for Image I see Recover HD.
finally. "diskutil list" typing in terminal list disks.
Please

My macbook air (OS x lion ) hard disk got crashed. now it starts with a grey screen and MAC OS X utilities. in the disk utility, the hard disk icon became inactive. when i erased the disk it became active again but i am still not able to partition it. it showed -- "Partition Error". "Couldn't unmount disk". now the disk icon became inactive again. when i click on mount it becomes active again but partioning is not done after many attempts.
another problem: - when it I click to proceed with the installation (still unpartitioned) it verifies my macbook's eligibility and says that the machine information is not with apple. below are the screenshots.
is there any internet issue, i got connected on my institute's wi-fi (excellent speed- 54mbps)

Help needed with delete of bootcamp partition, error message 'Couldn't unmount disk'

Hello all
Sorry if this issue has been repeated elsewhere, I did search but there wasn't a discussion relating to my specific issue.
When we bought the iMac a couple of years ago, my husband partitioned the hard drive to run Windows via Bootcamp. Having got used to the Mac and experiencing the frustration between having to reboot to access each partition I have decided to restore the Mac to factory settings and install Parallels 8 so I can continue to use Office and Coreldraw).
So having backed up all of my files, I started the Mac up holding the 'Alt' key and then loaded the Recovery HD mode followed by Disk Utility. I then selected Bootcamp and erased all data from the partition. [Note: there are 2 files left which it won't allow me to erase through this method]
I then selected the main drive and the tab 'Partition', from the layout I then selected Bootcamp and clicked the minus button. I get the message confirming which partition I am about to delete and hit remove. I then get the error message 'Partition failed: couldn't unmount disk'.
I would be very grateful for some help please? I am not the best techy person but happy to give anything a go.
Just to mention there is nothing left on the Mac that I want to keep, therefore if there is an easier way than having to delete the partition then happy to hear it.
Thanks
Tara

Hello Tara,
Are you using Filevault?
https://kimmo.suominen.com/blog/2013/03/file-vault-volumes-cannot-be-resized/
Also see the last few posts here...
https://discussions.apple.com/thread/3894449?start=15&tstart=0

I wanted to create two partitions on my iMac w/ Lion using a Recovery USB i created using Lion Recovery Disk Assistant but I keep getting Partition failed message saying "couldn't unmount disk"

I have this recently purchased iMac that comes with a Lion but I wanted to have two partitions on the hard disk. I know that the Recovery HD partition is on the same hard disk so I downloaded the Lion Recovery Disk Assistant and created a Recovery disk using a USB. I boot up the system using the USB Recovery disk and run Disk Utility to create 2 Partitions on the hard disk but I get a Failed partition message saying "couldn't unmount disk". What could be the problem here?

admench wrote:
Thanks for your continued help Tony. Do you mean normal boot into the regular operating system setting i.e. no keys held down in bootup? I think I have tried this, with the same result.
Yes, that's what I meant. If that doesn't work, verify that you have a G.U.I.D. partition scheme (you probably do):

Couldn't unmount disk

OK so here's the deal, I had windows 8 installed using boot camp, Then when I went to uninstall it using boot camp, it gave me an error message, when I closed everything, I opened boot camp and the remove windows 7 option was no longer there, it was install windows 7, so I opened disk utillty and there wasn't a boot camp drive, however, when I went to partitions, boot camp wasn't there but macintosh HD didnt take up all the space and there was a grey area beneath the Macintosh HD, I dragged the Macintosh HD to the bottom and clicked apply, I got an error meassage which I solved by repairing the disk. So when I try it again, the process progresses more and then I get another error message that says couldn't unmount disk. All of this done from the Recovery partition. What Im going to do now is put mountain on an external hard drive and boot from that and try again. Guys please HELP AND REPLY PLEASE!!!!!!!!
This is the grey area I was talking about, I tried repairing macintosh HD but I still get the same message

I had a similar problem as the thread starter, and was able to fix it by making a bootable Mountain Lion Recovery Volume on a USB stick, as Courcoul suggested above (http://support.apple.com/kb/DL1433).
I had removed bootcamp and the associated partition from my Macbook Pro running Mountain Lion, and I wanted to reallocate that space on the hard drive to my main Mac partition.
The bootcamp assistant had failed halfway through the process, and it could not extend the partition to include the unallocated space ("partition failed"). It had also created errors on my main Mac volume (when scanning with Disk Utility).
1) The Disk Utility inside Mac OS was not able to repair the volume, so I had to boot from the recovery partition (cmd + r during boot), and then repair them. This would let the errors be repaired, but still I would get the error "Disk Erase failed with the error: couldn't unmount disk" when I was trying to resize the partition to include the unallocated space.
2) So Finally, when booting from the recovery USB stick, and using Disk Utility, I was able to resize the main partition to the full size of the hard drive.
I think the error "couldnt unmount disk" was due to the fact that somewhere in the process it said it was trying to "relocate the recovery partition". So I assume that if you boot from this recovery partition on the drive, it cannot do this part, and the process fails.
Thank you all very much! Your comments were really helpful. I hope my explanation is useful to someone with the same problem.

Disk Utility "Couldn't unmount disk" in Recovery Mode

Hello, everyone. I'm dealing with a 15" MacBook Pro (April 2010) which seems to be unwilling to reformat its own hard drive. After several issues, the hard drive started giving the "Incorrect number of threads" error when Disk Utility's Repair Disk was run from within the Recovery Partition, after which, the computer refused to boot normally, going through a 'status bar' for a long time before shutting itself down.
I booted from the Recovery Partition once again, and attempted to have the OS X Mountain Lion installer format the hard drive, only for the existing boot partition to not show up in the drive choices menu. I then opened up Disk Utility once again, selected the hard drive (the main boot partition is greyed out in the side menu), and clicked Erase. The process started, with the diagonally-scrolling progress bar sitting at the "Unmounting disk" status for several minutes, only for an error to pop up reading "Disk Erase failed with the error: Couldn't unmount disk." Any further attempts to erase the drive resulted in the same error popping up instantly.
I rebooted the computer back into Recovery Mode, tried again, only for the process to repeat itself (albeit with thick gray vertical bars appearing on the screen, and a square made up of thinner gray horizontal lines appearing next to the mouse cursor, during the initial unmounting process!). Is there any way of saving this drive, or this Mac? Thanks in advance.
-Adam

You have hardware problems.
Make a "Genius" appointment at an Apple Store.
Back up all data on the internal drive(s) before you hand over your computer to anyone. If privacy is a concern, erase the data partition(s) with the option to write zeros* (do this only if you have at least two complete, independent backups, and you know how to restore to an empty drive from any of them.) Don’t erase the recovery partition, if present.
Keeping your confidential data secure during hardware repair
*An SSD doesn't need to be zeroed.

Time Machine error: could not backup, Disk Utility Error: Couldn't unmount disk

I recently bought a WD for Mac 1TB external drive which has been set up as Time Machine. This was as a result of my internal hard drive failing and being replaced. Time machine has worked a treat for last 3 weeks, but today I get a message:
Time Machine could not complete the backup.
Unable to complete backup. An error occurred while creating the backup folder.
So I go into disk utilities to verify the disk and I get this message:
Verifying volume “My Passport for Mac”
Checking file systemError: This disk needs to be repaired. Click Repair Disk.
I click on the Repair Disk and get this message:
Verify and Repair volume “My Passport for Mac”
Volume repair complete.Updating boot support partitions for the volume as required.Error: Couldn’t unmount disk.
last backup was at 3.53pm today.
Any ideas?

Why would I need to reboot the whole computer?
However, I did shut it down and restart it and the problem is fixed.

How to Erase Hard Drive Mac OS X (LION) "Couldn't unmount disk"

Hi Everyone,
I've just transferred my data to a new computer and now need to erase the hard drive on my old one.. I've tried Disk Utility, increased the security, and tried 'erase' but I keep getting an error message "couldn't unmount disk". I've gone into Partitions and tried deleting the HD there as well but I get the same message. Does anyone know the solution for this? I just want to get the computer securely wiped and would like to keep Lion as the operating system.
Thanks in advance!
-Eric

Hi Frank,
Thanks for the quikc response. I booted up in the Recovery Disk I believe. I held option at boot up and chose the recovery disk option. Is that the correct method?
I may have figured out what I was doing wrong. I was clicking on the parent hard drive reading "1 TB WDC WD1001Fals..." Now I've clicked on the next level hard drive "Macintosh HD" and I believe it is working.
Looks like 5 hours to erase...

External Drive Problem...Error "Couldn't Unmount Disk"

I have my Aperture Library on a 2TB External Seagate Drive, so that I can use it with both my iMac and MBP. It's been running really slowly lately, so I ran Disk Utility on it to Verify and Repair, and just got the error message "Couldn't Unmount Disk". Help, please! I have backup vaults, but they are months old because this has been so slow and I just got lazy. Ouch.
Sue

Hi Sue,
I would of course try this. Do you have all pictures organized by Aperture or referenced to from some Ext HDs?
If referenced, I would think of trying to organize the Library new.
The workaround suggestion: Copy the Aperture Library to one of your Macs
and run it from there (as you already asked). If it works fine, take another Ext.HD (maybe you are asked
by Aperture to repair because of any Inconsistencies, this takes most of the times quite long, but maybe helps),
and take care as before.
I wouldn't recommend Seagate HD's, but as always that's easy to tell afterwards.
It seems like the EXT HD has a problem and hopefully not Aperture.
This all is the reason for me, why I changed all pictures into referenced pictures, do my work, give names with Aperture, but keep the order in my hand. Back Up is of course as well in my responsability.
I've had always a bad feeling about letting something do the most important work, without knowing and take
care.
Uwe

Volume erase failed could not unmount disk

I have a Mac book Pro running 10.5.8 OSX. I'm trying to use Time Machine (need to replace the hard drive), and I bought a 1TB Toshiba portable hard drive. I read the instructions on the drive, which say that to use Time Machine, I'll need to reformat the drive as an HFS+. I found instructions to do that through Disk Utility --> Erase, with selecting Mac OS Extended from the Volume Format option. However, I keep getting the following message: "Volume erase failed. Could not unmount disk." I'm new to most of this, and have no idea what unmounting the disk is, much less how to resolve this. I found a thread that said to check my computer's name, which I did, but that didn't seem to help.

Likely where that second "Drive" came from, but may be gone now...
In Finder's Menu, select Go menu>Go to Folder, and go to "/volumes". (no quotes)
Volumes is where an alias to your hard drive ("/" at boot) is placed at startup, and where all the "mount points" for auxiliary drives are created for you to access them. This folder is normally hidden from view.
Drives with an extra 1 on the end have a side-effect of mounting a drive with the same name as the system already think exists. Try trashing the duplicates with a 1 or 2 if there are no real files in them, and reboot.
If it does contain data...
http://support.apple.com/kb/TS2474

Failure erasing and restore partition on PB, "cannot unmount disk"

Hi,
I would like to erase a partition that I have on my 30gb internal harddrive.
I get an error message saying something like "cant eject/unmount the disk" same error message when I run the diskrepair.
when I did the restore thing ( disk image of installdisk OSX 10.4) (I skipped the erasing and whent straight for restore) I got another error message. (saying something something and (-10000))
What can I do to erase the partition and restore

Calle:
I would like to erase a partition that I have on my 30gb internal harddrive.
Do you have more than one partition on the HDD? I suspect you have only one since the HDD is only 30 GB.
Your computer is now 8 years old, as is the original HDD. The average life of these drives is 3 to 5 years, so your HDD is well past old age. You may be getting the error messages because your drive is failing.
cornelius

"Couldn't unmount disk" error on internal HDD

This thing wa posted before but all solutions and suggestions didn't work for me.
I have a MacBook Pro that won't start up from its internally installed OSX Lion anymore. So, this is what I have done so far:
From the system itself, Disk utility: Repair disk permissions, repair disk, resizing partitions, deleting recovery (yes, that is possible)
From the internal Recovery Partition, Disk utility: Same stuff plus repartitioning, reinstalling
From a Mavericks installation on an external drive: Same stuff plus erasing and repartitioning the disk, force unmount via terminal (and yes, I cut off spotlight to ensure it is not indexing the internal drive)
From a mavericks install stick: Reinstalling (Partition doesn't show up), and the above stuff.
Both external Disk Utilities keep producing that error, and now for the strange part: Disk Utility shows the internal Macintosh HD Partition as unmounted and the Hard Drive itself mounted.
single user mode told me that the catalog hierarchy is corrupted - I thus assume it cannot be defective hardware.

inlackoftime,
please try booting into Recovery mode again. From the Utilities menu in the menu bar, select Terminal. In the Terminal window, give it the following commands:
diskutil list
mount
Please include in your reply the full output from these commands.

Error: Couldn't unmount disk -- when trying to verify/repair external hard drives. Has anyone had this problem and solved it?

I have a number of hard drives that my Mac Book Pro no longer 'recognises' at least for very long. When I turn them on the deskstop icon shows up but then shortly afterwards I get a message saying that it has been unplugged incorrectly. I haven't unplugged it any of them. When I try to run very/repair disk before they disappear I get the error in the subject line above. Has anyone had this problem and if so how did you rectify it?

The drive is malfunctioning and needs to be replaced, or you have some other hardware fault.
Make a "Genius" appointment at an Apple Store.
Back up all data on the internal drive(s) before you hand over your computer to anyone. If privacy is a concern, erase the data partition(s) with the option to write zeros* (do this only if you have at least two complete, independent backups, and you know how to restore to an empty drive from any of them.) Don’t erase the recovery partition, if present.
Keeping your confidential data secure during hardware repair
*An SSD doesn't need to be zeroed.

TS1550 "Partition failed - couldn't unmount disk"? what next?

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