Racavi
Level 1 (0 points)

Q: How can I uninstall Yosemite and back to Snow Leopard?

I installed Yosemite OSX but I have problems with some of my App, because are not compatibles with this OS version, so, I need to uninstall Yosemite and back to my preview OS which is Snow Leopard.

Posted on Feb 5, 2015 4:48 PM

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Racavi

Q: How can I uninstall Yosemite and back to Snow Leopard?

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  • by babowa,

    babowa babowa Feb 5, 2015 5:05 PM in response to Racavi
    Level 7 (32,049 points)
    iPad
    Feb 5, 2015 5:05 PM in response to Racavi

    Do you have a backup of your system?

     

    If you want to go back to Snow Leopard, you will need to erase your hard drive first and then reinstall from your backup.

  • by MichelPM,Helpful

    MichelPM MichelPM Feb 5, 2015 7:38 PM in response to Racavi
    Level 6 (13,791 points)
    iPad
    Feb 5, 2015 7:38 PM in response to Racavi

    If no backup, you will NEED to get a complete backup, first. Then, you can boot from your Snow Leopard install disc. Once booted from the SL install disc, quit the Installer app to return to the OS X Finder. Then, launch the Disk Utility app on the disc to erase your Mac's hard drive, then relaunch the Installer app to re reinstall OS X Snow Leopard. Then update OS X Snow Leopard using the OS X Software Update feature, in the OS X Preferences Panel, to update OS X to 10.6.8. Next, reinstall all of your third party applications, then restore your data from the backup you made.

  • by babowa,

    babowa babowa Feb 5, 2015 7:46 PM in response to MichelPM
    Level 7 (32,049 points)
    iPad
    Feb 5, 2015 7:46 PM in response to MichelPM

    FWIW, I just went through this mess; I was trying to get a mid 2010 iMac (originally with SL) ready to sell with the original OS installed. I was not able to boot from the install disk because Macs which had their firmware updated to allow internet recovery when Lion was introduced can no longer boot from an SL install disk - the firmware prevents it. I had to boot from a previously made external clone of SL and erase my hard drive first. After that, I was able to use the install disk to install SL.

     

    This was the second time I encountered this (the first time I was just testing different scenarios).

  • by MichelPM,

    MichelPM MichelPM Feb 5, 2015 11:43 PM in response to babowa
    Level 6 (13,791 points)
    iPad
    Feb 5, 2015 11:43 PM in response to babowa

    I was never, EVER aware of this!!!

    Is this issue just related specifically  to OS X Lion?

    Or something that happens at every newer OS X upgrade to the internal hard drive?

    I only updated directly to Mavericks from Snow Leopard and my Mavericks OS was installed onto and is still on an external hard drive.

    Is this something I need to worry about when and if I clone my Mavericks OS to my internal hard drive?

  • by babowa,

    babowa babowa Feb 6, 2015 8:31 AM in response to MichelPM
    Level 7 (32,049 points)
    iPad
    Feb 6, 2015 8:31 AM in response to MichelPM

    It's become really complicated.........

     

    I know I did this firmware update back when Lion came out (and it's for mid 2010 27" iMacs):

     

    http://support.apple.com/kb/DL1493

     

    There is this list for all firmware updates:

     

    http://support.apple.com/en-us/HT201518

     

    I believe (but may be wrong) that the 2010's were the "oldest" machines one could "reset" to be able to boot into internet recovery. I don't know about any other firmware updates which specifically enabled older machines to run internet recovery. Once that is applied, it makes changes that will prevent booting from the SL install disk - at least on my machine with that EFI update applied. I did some testing about a year or so ago and found the same problem (I also found that internet recovery is not at all reliable on my machine - sometimes reinstalling Lion after a complete erase (why???? finally figured it out I think: probably because it is not able to reinstall the original OS since that's not available on their servers) and sometimes installing Mavericks (even though I had erased the whole thing). So, to me, it's not really usable if it's not reliable and doesn't do what it is advertised to do. It is possibly because the 2010's are the last machines with Snow Leopard/install disk and they made an attempt to make them work without one.......

     

    Edit: If you've never installed the firmware update, you should be fine with an SL install disk.