How to Resolve a “Partition Failed” Error in Mac OS X

Mar 5, 2012 - 63 Comments

Partition Failed error

If you have attempted to partition a drive from Mac OS X and received a “Partition failed” message with the error “Couldn’t modify partition map because file system verification failed.” you can fix the problem with the file system check command line utility. To do this properly, you’ll need to boot into Single User Mode as well:

  1. Reboot the Mac into Single User Mode by holding Command+S during boot
  2. At the command prompt, type:
  3. /sbin/fsck -fy

  4. When fsck is complete, type “exit” or “reboot” to reboot
  5. Boot the Mac as usual, verify the disk again in Disk Utility, and partition as usual

Boot the Mac as usual and relaunch Disk Utility to verify the disk. Go ahead and partition the drive as usual, this time without any such error message.

I have encountered this error a few times when partitioning the boot drive from OS X Lion, most recently after a clean installation when setting up dual boot for OS X Lion and Mountain Lion. The cause of this remains to be seen, and repairing the disk from Disk Utility itself doesn’t work, even when in Single User Mode or when booting from another drive.

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Posted by: AJ in Mac OS X, Troubleshooting

63 Comments

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  1. Ron says:

    Thanks for posting this… I had this exact error last week!

  2. Yoni says:

    Thanks a lot. I was looking for something to fix that since ever !

  3. Brandon says:

    Before you bail into the command line… this error will occur depending on the sequence of your clicks and drags on the partition map. It seems to be, at least partially, a calculation error, programming parlance is “fence post.” The fsck (filesystem consistency check) utility should be used with some caution however. Please see http://support.apple.com/kb/TS1417?viewlocale=en_US&locale=en_US

    -b

  4. Gnometosser says:

    I had this same issue and fsck did not fix it for me. I ended up using super duper copy to make a backup image on a USB drive then booted from the backup drive and used super duper copy format the drive and copy the files back to my main hard drive. It worked great and I was able to make a 200gig windows 7 partition on my early 2009 iMac.

  5. hendrik says:

    worked great – looking for this for a long time !
    txs!!

  6. LouDAT says:

    Spot on. Worked like a charm. many thanks!

  7. Ed says:

    Thank you! I tried removing a Boot Camp partition on my File Vault encrypted drive and encountered this issue. Switching off File Vault didn’t resolve it but following these instructions did.

  8. KK says:

    Thanks thanks. This saves me from hours trying to get a partition to install windows on my mac.

  9. clayton says:

    Thank you! After searching all over the place, this finally did the trick. My Boot Camp partition succeeded immediately.

  10. Sebastian says:

    Help!!! I was trying to do a BootCamp so i can install windows 7. I found this as a solution to my problema, but after i did this, my hard drive is full and i just have 10 gb of free space, it says:
    Audio: x.x GB
    Movies: x.x GB (THE X’s are just examples, not real GB’s)
    .
    .
    Other: 320.5 GB !!!! WTFFF, PLEASE HELP ME HOW CAN I FIX THAT

  11. Alvin says:

    Thank you for posting this online it has saved me alot of time and prevents from reformatting disk and starting from scratch. You are a legend.

  12. Nasir says:

    Just I want to say thank you, really I spent two days to find any solution to this problem. Worked great

  13. vb says:

    really worked for me. Many thanks

  14. Andy says:

    Worked like a champ! Thanks!

  15. Justin says:

    I tried the fsck and it couldn’t be repaired after 3 attempts. What now?

  16. litium258 says:

    yes, it worked right away. i’m new to mac so i wanted to do dual boot with windows and made my partitions with disk utility, when i tried boot camp it told me the disk should be one partition only…the problem arised when i deleted my previous partitions and trying to enlarge the main partition to full size.

  17. cooltips says:

    thank’s man it’s really worked, removing boot camp partition

  18. hhazm says:

    juste force quitting itunes

  19. Mark says:

    Thanks for the tip! Got this error when trying to resize Bootcamp partition during the Winclone process. Your solution worked for me.

  20. Sri says:

    Saved my day. Thanks!

  21. Paul says:

    Fantastic! Worked perfectly!

  22. Grant says:

    Thank you so much this help me a lot!!!

  23. Tony says:

    Many thanks. Much appreciated.

  24. Raf says:

    Hello,
    I have a problem with this.
    I have a ssd as my main drive for running mac and have a hdd instead of my superdrive. But I want to keep part of this secondary drive cause it has my photo/music/… library on it.

    Is there a similar command that could fix this for the secondary hard drive? Just as easy as this so I don’t need to replace all files (250+gb) to an external and back?

    Please send me a mail or something, would be much appreciated !!!

  25. AOA says:

    thanks that was big help for our Community

  26. John says:

    Thanks but just the restart worked for me

  27. Miguel says:

    I had the same problem: could not create a partition. Followed these instructions and voilá, it worked right afer that.

  28. Trevor says:

    Finally fixed my problem partitioning. I took a screen shot of the process too. It was missing some blocks on the HDD:

    ** Checking volume information.
    Invalid volume free block count
    (It should be 63457968 instead of 47085599)

    After that, it repaired it and checked it again. Then the employee (I work in IT) explained that he was missing 150-200GB’s of free space on his HDD. That showed up also. Finally able to partition after this. Tried many other ways of fixing it. He can finally dual boot to Windows 7 and Mountain Lion. Thanks!

  29. Ash Nagar says:

    hi

    for me the error msg is not this…instead –

    “The disk cannot be partitioned because some files cannot be moved.”

    so if its the same as the above then shall i do this process or what should i do…i have macbook pro with mountain lion 10.8.2

    thx
    ash

  30. Ash Nagar says:

    oops! sorry for the double post didnt realize i had already posted…my bad…

  31. kewldude says:

    Excellent article!!
    While removing windows 7 boot camp partition via BCA tool on OS X Mountain Lion, it complained “failed to remove”.

    However after rebooting MacBook Air noticed that Boot Camp was gone but was not able to merge the partition using Disk Utility. It gave the same message as in this article. Followed the steps in this article and after rebooting everything works perfectly.

    Happy to recover the unused 50GB of Win7 on my 128GB MacBook Air.

    Thank you so much!!

  32. Elroy says:

    Thanks. I love it when what I read online actually works.

  33. James says:

    I typed /sbin/fsck -fy exactly and it says it is not recognized. Not sure what I am doing wrong.

  34. Steven says:

    This fixed a problem I had trying to recreate a bootcamp partition. Thanks!

  35. George says:

    THANK YOU!

  36. krishan says:

    sweeeeeeeeeeeeet worked like a charm….

  37. Hassan says:

    Thank you very much !! it fixed my problem and i installed windows normally :D thanks a lot !!! very good fix !!

  38. Aalaap Ghag says:

    If you have rEFIt installed, the startup commands (Cmd+S) won’t work. But this is simpler to do in rEFIt: just hold Option for the menu to come up, then hit F2 and select ‘Boot into single user mode’. Then run the command mentioned above and voila!

  39. tibinet says:

    Hey man, you saved 20GB from my 128GB SSD. Thanks a lot!

  40. Ben says:

    Hi, I tried this and now Mac OS X 10.8 won’t boot. The grey Apple loading screen now has a loading bar on it, and when it gets to the end, the Mac shuts down.

    Help anyone?

  41. Stanley says:

    Hi,
    i had the same error,
    just try the suggestion but still same error msg still occured.
    need help.. thanks

  42. Donald says:

    Thanks a lot! this worked like a charm!

  43. [...] when attempting to modify partitions on a drive, which came right along with a separate “partition failed” error, and again was triggered when attempting to format those partitions. The above steps [...]

  44. [...] but if Disk Utility throws an error it’ll probably be either ”Couldn’t unmount disk” or a “Partition Failed” message, both will require a reboot and slightly different methods to resolve, and can be mitigated by [...]

  45. Emma says:

    Great helped. Thank you very much!

  46. Andi says:

    Thank you veeeeeery much, i am finally able to abandon annoying Mac OS

  47. Am enormously grateful. My machine was all messed up with my attempts at partition. This cleared everything up beautifully, and I now have two handsome partitions. Thank you.

  48. abhilash says:

    Lot of thanks…it is working for me …

  49. Lexlovey says:

    Hi, i need help.

    after i type in the code.
    it says that;
    Incorrect block count for file SystemEntropyCache
    (It should be 1 instead of 0)
    Incorrect block fcount for file sqlindex-shm
    (It should be 8 instead of 0)
    Keys out of order
    (4305)

    what should i do?.

    can email me the solution for it?.

    Really appreciate a lot for your help.

  50. Cary says:

    Thx! Removing a bootcamp partition gave the error. All good now!

  51. Michael says:

    Thanks a million! Worked like a charm on my 2011 MBP running Mavericks.

  52. lee says:

    I was attempting to partition my mac mini (currently been in use for over a year) in order to install windows via book camp.

    I attempted your fix and did as you instructed and still had the same error message come up.

    Is there anything I need to do to “reset” my mac to the way it was before I entered that short commands at the command prompt after pressing Command+S during startup?

    thanks.

  53. Ron says:

    I tried this and now my machine won’t boot. Great.

  54. Faris says:

    It worked! Teach me master..

  55. Vishal says:

    Could it be a part of directory structure corruption error? Seems like an early warning. However, a Mac can’t repair directory on its own. A tool like Tech tools pro or Stellar Volume repair may be needed to replace the bad dir structure.

  56. Shen Long says:

    Wonderful write up, my hdd can be resized again :)

  57. Peter says:

    Thank you! I got my 30GB back!

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