‘The disk you inserted was not readable by this computer.’ Fix

Have you seen anything like this before?

In my case, if I load my Kontakt 4 sampler (as standalone) with external USB hard disk with time machine backup system activated, the disk just shuts down and never comes back again. And if I plug the USB port again, I get the message ‘The disk you inserted was not readable by this computer.’ and the disk is still not operational. I can’t understand the whole situation, but I assume it’s some kind of logical error on the Mac OS file system.

Anyway, since I was using it as a backup drive, I just did a clean format and backup the system from scratch, until now. But after some research, I’ve found out that it can be fixed very easily with a single terminal command.

If you get the message above, click ‘Initialize’, then ‘Disk Utility’ will pop up. Ignore disk utility, and run ‘Terminal’, then type

diskutil list

(check your hard disk ID)


sudo gpt recover /dev/disk3

(insert your hard disk ID instead of disk3)

Type in the password if asked. It’s done. try to plug in your USB port again and check if it works.
Of course all of your data should be fine.

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51 Responses to ‘The disk you inserted was not readable by this computer.’ Fix

  1. Casey S says:

    After typing that in Terminal, the response was: “no primary or secondary GPT headers, can’t recover”

    Any suggestions??

  2. Gepe says:

    I’m just having the same problem now… does anyone have already results with this method?

    • shunu says:

      like I said above, check your disk ID..

      it will look like disk1, disk2,

      replace your disk ID with disk3
      sudo gpt recover /dev/disk3

  3. jojo says:

    my disk ID is disk1

    I have the following msg too -

    gpt recover: /dev/disk1: no primary or secondary GPT headers, can’t recover

    • shunu says:

      Hi jojo….

      unfortunately.. this method doesn’t work for all circumstances…
      I guess the disk is damaged for good.

  4. hodgo says:

    I’m confused about the password. In Terminal, I typed in sudo gpt recover/dev/disk2 (my external Lacie drive) and was asked for a password. Is this the password for the external drive? I don’t usually put passwords on my drives. I hit return because I suspect the drive has no password, but Terminal kept asking me for a password.
    This was my backup drive. (I had made many, many back up DVD’s, but to chaotic circumstances, they are lost and the drive died before I had a chance to back up everything.) Initially, the drive wouldn’t start up, which I attributed to the drives power supply connector. I had a tech guy (who claimed he was dual platform) look at it and he replaced the drives housing. Now, the drive does power up but won’t mount. I tried disk utility and got this error message: filesystem verify or repair failed.
    I called to the tech guy and he didn’t have any answers for me. I’m not a tech guy and don’t know the proper tech lexicon to be looking for answers online. So, now I’m at a loss for what to do. Ideas or advice, please.

    • shunu says:

      the computer is asking for the user password. the password when you put in to log into your main desktop.
      if you want to change the password, type…
      check System Preferences-> users & groups then check the current user and you’ll see ‘Change Password’ on the right side.

      • hodgo says:

        Thank you for your reply. If anyone is having the same problem, here is what I did: I didn’t have a password assigned to my laptop. Terminal kept insisting I put a password in so I went to systems prefs and added a password. Doing that got me to the next level. (where it asks for the PW hint, I typed in the PW in case I forget it.) I then typed in “sudo gpt recover/dev/disk3″ in Terminal (disk3 is the correct disk for me) but now I get a message “gpt: unknown command: recover/dev/disk3″. I used a program called Disk Drill to scan the drive. It took nearly 72 hours to scan my external Lacie T1 drive. What I didn’t know when I downloaded the “free” software was that I need to upgrade to the Pro version ($75) to recover the data, which I’ll do. In the meantime, I’m running DiskWarrior, which has been stuck in Step 1 (searching entire dsk in final rescue attempt) for several hours. I researched this online and several folks have had this issue, some saying it took nearly a month for DW to repair the drive.
        Question: Why is Terminal telling me the command is unknown? (oh, the drive the formatted for Mac, no partitions but DU says Partition Map Scheme :Apple Partition Map, SMART status not supported.)
        Lastly, I’ve read a lot of things saying “back up, back up, back up your drives.” Here’s the thing: I did back up this drive. I had about 75 cds and DVDs of back ups. We moved and I put the back up disks in a box which never made it to our new flat. I didn’t know this until two weeks later when my drive died. So, back up, but put your back ups either in a safe deposit box or on a cloud. Thanks for reading. Any advice or comments sincerely appreciated.

        • shunu says:

          hello again hodgo~
          thanks for telling about your frustrating experience….. I’ve been using computers way back from apple 2 era. and yes… I know this for sure… “never trust hard drives.”….2 hard drives failed on me during the latest 3 years. place your files in 2 separate disks all the time. if I had your experiences.. maybe I’d just think “oh the disk is dead.”
          anyway. congratulations for fixing the disk~ ;-)

  5. Mike says:

    Worked like a charm for me. Thanks!

  6. frayfray says:

    where do i find terminal after going to disk utility?

    • shunu says:

      no no~ just ignore disk utility and go to

      finder->application folder -> utilities folder -> terminal.


  7. Isabella says:

    It doesn’t seem to be working….

    I type in sudo gpt recover /dev/disk0
    But it says:
    gpt recover: unable to open device ‘/dev/disk0′: No such file or directory

    Are the spaces correct and am i choosing the right number?
    The one at the top that says /dev/disk0 or the identifier that says disk0s2?

    • shunu says:

      the disk0 should be fine..(no 0s2 or s3) I just want to see your computer myself… hum… did you check by typing diskutil list?

      • Isabella says:

        Yes i did and it had a top one that said /dev/disk0 and another was /dev/disk1 i think for the usb that isn’t working…

        will try again and see what happens

        • Isabella says:

          It asked for the password this time but it said
          gpt recover: unable to open device ‘/dev/disk0′: No such file or directory
          Do i insert the USB stick before or after typing in the password?

          • shunu says:

            It’s really difficult to understand the situation by only seeing the text. but this method doesn’t cover all cases for logical errors. maybe your disk is already dead. try clean formatting it, if you just want to use the disk.

  8. Racquelle says:

    Hi! I’m receiving the same message. However, after going through all the steps and proceeding with the password, it says “gpt: unknown command: recover/dev/disk1″ What do I do now?


  9. Steve says:

    Hi, I got the same error message and I am down to the password part of the Terminal. Then it says something like “make sure you type sudo correctly….or you could loose important files or data”. I am certain that I followed the directions and my ID is correct but I am still a little hesitant to put the password in and enter because of the warning. What’s the worst I could do if say I didn’t do the spacing correctly or something? Thanks in advance for any response! Cheers!

    • shunu says:

      Hi steve~ I assume that your disk is unavailable at the moment anyway. so is there a reason not to try it?

  10. Ellie says:

    I got the same message as steve there, and I too am very hesitant.. I can’t afford to lose these files. What are the chances that it will work? And if the command doesnt work, what are the chances that it’ll just leave it be and not do an entire restore? Thank so much, you’re definitely a big help. A little panicky here.

    • shunu says:

      first. try to connect it in a different mac or any computer. then do the same thing as above. see what it has to say. the command only works on mac os journeled GPT formatted disks BTW.

  11. Matty says:

    I typed in the password wrong at first and then when i retry the steps i get “gpt recover: unable to open device ‘/dev/disk2′: Input/output error”

    any idea?

  12. Bob Mc says:

    I got a similar message when I inserted a music cd, but it did not have the ‘initialize’ option, just that the cd is not readable by this computer. with ignore or eject.
    All other music cd’s play fine.
    Any suggestions?

  13. marzzz says:

    After I type the command I get the following message:
    gpt recover: /dev/disk1: error: device contains a MBR

    What should I do?

    • shunu says:

      Hi! that means your hard disk is not formatted as GUID Partition Table. try to check the disk with disk utility.

      • marzzz says:

        Hi shunu! Unfortunately when I select it on disk utility, the verify disk and repair disk buttons are turned off and I cannont click on them… I don’t know where else to turn! Any ideas? Thanks!

        • shunu says:

          HI!~ you’ll have to boot through the install partition(disk if snow leopard) perhaps. press alt when you here the first chime of the mac.

          • marzzz says:

            Hi Shunu, first of all thank you so much for your time and help. When I press alt, the disk with which I’m having problems does not appear (only the HD of my laptop appears, not the external disk with the problem)… Any advice on that??? Thanks!!

      • Alex says:

        After I type in, sudo gpt recover /dev/disk3. They ask for password, when I type in password nothing happens. I can’t type anything in. Only the enter key works.

      • Max D says:

        I had the same problem. I plugged my iPod into iTunes and for some reason, it wiped out all 24,000 of my songs. Depressed, I started to put them all back from my external hard drive — which subsequently locked up and then wouldn’t be recognized by either my Macbook or Dell notebook. This is what I got in Terminal…
        gpt recover: /dev/disk1: error: device contians a MBR

        You said “That means your hard disk is not formatted as GUID Partition Table. try to check the disk with disk utility.” What exactly does that mean?


      • Max D says:

        I had the same problem. I plugged my iPod into iTunes and for some reason, it wiped out all 24,000 of my songs. Depressed, I started to put them all back from my external hard drive — which subsequently locked up and then wouldn’t be recognized by either my Macbook or Dell notebook. This is what I got in Terminal…
        gpt recover: /dev/disk1: error: device contians a MBR

        You said “That means your hard disk is not formatted as GUID Partition Table. try to check the disk with disk utility.” What exactly does that mean?

        PS – It was actually PC formatted. So what is a similar method to repair this problem on a PC?

        • shunu says:

          there are 2 kinds of disk partition table.. GUID Partition Table, Master boot record. if it’s formatted on windows, it’s likely a MBR table. go to windows and try disk error check. but I do not think the disk is 100% OK.

          • jack says:

            I have the same problem on one of my macs with 10.6.2 but not on another mac with 10.6.8. My hd is formated ntfs and I suspected nothing wrong with it before trying to use my older mac. Mac sure your software is up to date.

  14. Mario says:

    Dude! you saved my day, I was crying since I thought I was lost all my info but I could saved it!! god bless you brah! cheers from Mexico!

  15. nancy says:

    how do i know which disk? there are several options: under one called “/dev/disk0″ there is: disk 0, disk0s1, disk0s2. and then there is another called “/dev/disk1,” which has disk 1, disk1s1.

    is the /dev/disk0 data on my laptop and /dev/disk1 my external hard drive data? in which case, i should type “sudo gpt recover/devdisk1″?

    when i type that, it gives me a warning: WARNING: Improper use of the sudo command could lead to data loss
    or the deletion of important system files. Please double-check your
    typing when using sudo. Type “man sudo” for more information.

    and also i need to input a password

  16. pattapong says:

    hi there i was follow the step but it told me this “gpt: unknown command: /dev/disk0″ so how to fix it?

    • pattapong says:

      sorry but its not “gpt: unknown command: /dev/disk0″ but it said “gpt recover: unable to open device ‘/dev/disk0′: No such file or directory”

      and here is the command from sheck diskutill list
      0: GUID_partition_scheme *320.1 GB disk0
      1: EFI 209.7 MB disk0s1
      2: Apple_HFS Macintosh HD 276.0 GB disk0s2
      3: Microsoft Basic Data BOOTCAMP 43.8 GB disk0s3
      0: FDisk_partition_scheme *500.1 GB disk1
      1: DOS_FAT_16 500.1 GB disk1s1

  17. George says:

    My life is on my external drive and have no backup =( I am getting this message. Tried your method, and after my password get:
    gpt: recover: unable to open device ‘/dev/disk2′: Resource busy

    Not sure what I can do….besides pray and plan to back up asap if I can get it open!

    Please help =) Thanks!

  18. Elijah says:

    Hello, well does this work with WD hard drives? I tried it and I get an error after entering my password saying ‘Suspicious MBR at sector 0′ and ‘device contains a MBR’ Do you have a fix for this?

  19. Alok Singh says:

    when I did all this there was a error saying “device contains a MBR”…
    Help me My drive is working fine in Windows

  20. nana says:

    hi i have done everything u said but when i type in my password for some reason the letters don’t appear on command terminal and then i press enter and all i get the name of my computer why???? pls help!

  21. Sagar says:

    I tried this option but getting the same message again. “The disk you inserted was not readable by this computer” Somebody please help!

  22. pp says:

    gpt recover: unable to open device ‘/dev/disk1′: Permission denied

    how to ?

  23. Mike says:

    I got the following error: “gpt recover: unable to open device ‘/dev/disk1′: Resource busy”

  24. Craig says:

    I’ve been having this same problem/error message. I just upgraded to OS Mountain Lion. Before upgrading I didn’t have any problems with this drive (iomega 1T), infact, I’m certain there isn’t a problem with the drive but with Mountain lion, because if I plug the same external drive into my other machine that is still using an older OS. it works just fine. I’ve tried your trick here in Terminal and get the message “no primary or secondary GPT headers, can’t recover” after I put in my password…
    Any idea what else might be going wrong?

  25. judy says:

    Thanks so much for this!

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