4 Replies Latest reply: Nov 7, 2012 6:26 PM by Yuengdog1983
Twisted Innovator Level 1 Level 1

My software is up to date...and all I need to do is install Mountain Lion.  I get all the way to the choosing a disk(the only ones that shows up, Machintocsh HD...then this message pops up..."This disk cannot be used to start up your computer" ***?.....


Yep, I need some assistance please.  Can anyone help me?.....

  • thomas_r. Level 7 Level 7
    Apple Watch

    What version of the system are you currently running? Is your machine capable of running Mountain Lion? (See the specs.) If there's no reason that your hardware can't run the system, it may be that your hard drive has the wrong partition map scheme. It needs to be GUID in order to be bootable in Mountain Lion. Use Disk Utility to determine what the current partition map scheme is:


    Screen Shot 2012-11-07 at 1.53.01 PM.png

    Note that if it's not GUID, the only fix is repartitioning the hard drive, which requires erasing it.

  • Twisted Innovator Level 1 Level 1

    Thank you for the help Thomas,


    I have the latest version of Snow Leopard v10.6.8.  I read what apple says that requires me to be able to download ML and my disk utility also says GUID Partition Table on the bottom right...like your snap shot.  It gets my past initial download and disclosure statement scene, but then when I click the Macintosh HD....that's when the error pops up about the disk.  Also, when I go to disk utility and click on the HD...the partition tab is not there.  It only shows: First Aid, Erase, RAID, and Restore. I clicked First Aid and did the Repair.  I also clicked on Erase and did that too.  Those two still did not fix it......

  • thomas_r. Level 7 Level 7
    Apple Watch

    You have to select the physical drive itself (named "500.11 GB ..." in the image), not the volume (named "Hyperion" in the image), otherwise the Partition tab does not appear. However, if it already says GUID, there's no need to repartition the drive. Have you already erased it? It sounds like you have.

  • Yuengdog1983 Level 1 Level 1

    Follow the instructions on this article and you should be fine

    Essentially you have to adjust the partition for Macintosh HD temporarily