Possible to upgrade os from startup options?

Discussion in 'macOS' started by cameronjpu, Mar 10, 2015.

  1. cameronjpu macrumors 65816

    Aug 24, 2007
    I think I have done this before, but before I tried again I wanted to check with others to make sure that I was correct. What I need to do is upgrade a lion system to Mountain lion, but when I try to run the installer from within Mac OS, it goes nowhere because of some corruption issues I think with the installer within Mac OS. What I think I can do is boot the computer with the option key to my bootable Mac OS USB stick and install from there.

    What I want to verify is that I can do an upgrade in that way, not just a clean install.

    Any confirmation that that's possible?
  2. Taz Mangus macrumors 68040

    Taz Mangus

    Mar 10, 2011
    Yes that will work.
  3. Bruno09 macrumors 68020

    Aug 24, 2013
    Far from here
    You don't even need to boot from the USB stick.

    The installer is at the root of the stick.

    Double click on it to run it.
  4. cameronjpu thread starter macrumors 65816

    Aug 24, 2007
    That will not work for the reason I laid out in my post.


    Thanks will try tonight
  5. cameronjpu thread starter macrumors 65816

    Aug 24, 2007
    Update for the next guy reading this after a Google search - all done, success!

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4 March 10, 2015