"OS X cannot be installed" :( ?!

Discussion in 'OS X Mountain Lion (10.8)' started by PNayo92, Jul 25, 2012.

  1. PNayo92 macrumors member

    Jan 1, 2011
    I'm running an early 2011 macbook pro with Lion and I just downloaded Mountain Lion. I can't install it, though, because it says that my "Mac OSX" drive cannot be used to start up the computer (even though I do use it).

    I think the problem might be with bootcamp. Do I have to un-partition my hard drive before I can install mountain lion? I hope not :/

    Can anyone help me out?
  2. arashb macrumors 6502

    May 3, 2009
    You can try these methods in this thread, but I'm not sure how it would work since you have Windows.

    Or you could just delete the partition and try to do a clean install over the OS X partition, but you may have files you need there.
  3. Dissecta macrumors member


    Jun 5, 2007
    Edinburgh, UK
    Have the same issue here. Still investigating, not keen on the suggestion on the web page it directs you to saying erase disc and install 10.6...
  4. Romanesq, Jul 25, 2012
    Last edited: Jul 25, 2012

    Romanesq macrumors 6502a


    Jun 16, 2003
    No install direct on Lion drive

    You can't install it on the same drive as Lion. You have to create an install disk. Sorry, I missed one step:

    You do that by taking the dmg file of Mountain Lion and open disk utility.
    - go to the ML application and "show contents"
    - Mount the file in the container as "source"
    - Make the destination either an external usb drive or stick
    - Let disk utility do its thing
    - it will create a Mac OS X Install Disk at that location
    - reboot with your finger on the option key
    - you can then choose to boot from the usb external drive or stick

    Install your mountain lion on your internal drive where Lion resides.

    You can do this install then on other macs in your home too. :p

    P.S. If you want to do a clean install. The copy your Lion drive first and then erase it before the install from your newly created Mac OS Install "disc."

    go get'em!
  5. PNayo92 thread starter macrumors member

    Jan 1, 2011
    Maybe it has something to do with there not being enough extra room on the hard drive to install. I read this article:


    on installing Lion with the same error message. It says to repartition the Mac OSX drive to a smaller size, install, and then size the partition back to normal. I don't know if it would apply to 10.8 though..

    Thanks, Romanesq, I'm going to try it out =]
  6. andrewcroberts macrumors newbie

    Jul 12, 2011
    I had this, with Snow Leopard to Mountain Lion on an older Mac. I seem to remember, that I went into Disk Utility, clicked the main drive, partition tab, and resized my "Macintosh HD" to make it ever so slightly smaller. About 100MB smaller. Then the install would work (after quitting the installer and relaunching).I then expanded the partition after the install.
  7. Dissecta macrumors member


    Jun 5, 2007
    Edinburgh, UK
    *I am NOT recommending the following, this is just what I am trying and it may not be successful*

    Hmm split my disk into two partitions (I only currently have about 170GB of data) and Mountain Lion seems to be happy to install onto the second, so my logic is to delete my original partition and then restore my time machine backup onto the new disk.

    Does this seem like a good way forward or am I about to hit a world of hurt.

    I tried using the original partition after the split and still got the cannot be installed error.
  8. edholmes macrumors newbie

    Jul 25, 2012
    I had this! You probably don't have a recovery partition so ML wants to make a new one. To do this, resize Macintosh HD and make about 500mb of free space then try it again. If you get errors doing this, try doing if from Internet Recovery (restart holding Cmd + R ) Hope this helped you, it helped me. Although i had Ubuntu on it and I wiped it off my system. Just to be safe :cool:
  9. PNayo92 thread starter macrumors member

    Jan 1, 2011
    I tried making the Mac OSX partition smaller by a couple GBs. It said "error, could not partition. Change in size is too small"

    The error still occurred even when I tried making it smaller by 20 GBs. No me gusta
  10. PNayo92, Jul 25, 2012
    Last edited: Jul 26, 2012

    PNayo92 thread starter macrumors member

    Jan 1, 2011

    Hey, so I made a disk and tried rebooting onto it. Once on the install disc, it still gave me the same error: that I couldn't choose Mac OSX because it couldn't be used as a startup disc.

    I also tried reducing the partition size of my Mac OSX in an attempt to change the error, but it could not be re-partitioned because the "change in partition size is too small"

    I'm thinking I might have to reformat and do a clean install...not sure how it will affect bootcamp or how long it will take. I have time machine and an external hard drive with backups.. I just hate reformatting (last time I did was when my macbook pro crashed).


    So, I did a clean install. Used a time machine backup on my external harddrive, and a DVD install disc of mountain lion (that I made using disc utility). It took about 10 minutes to boot up to the DVD, but other than that, everything went smoothly.

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