I’m running OSX 10.8.5 on my MacBook Pro Retina.
I’d like to update my OS to the latest, but I’m using legacy FCP7 for a few important projects.
I was advised to install OSX 10.8.5 onto an external drive to boot off of whenever I needed to use my legacy FCP, but when I tried to do that from the install window, it doesn’t allow me to install on any of my external HDs (all have plenty of room). The error message says, “OSX Update can’t be installed on this disk. reaures OS X version 10.8.4 or later. So then I tried downloading 10.8.4 and installing that. And I got the same error message, even though I was trying to install the same version: 10.8.4.
Get an external drive that is at least the same size as your current internal 10.8.5 drive
Get Carbon Copy Cloner (CCC) software (it’s free to try)
Use CCC to make a copy of your 10.8.5 drive to the external drive
Reboot your Mac and hold down he Option (⌥) key when you hear the boot chime
When you see the screen that shows multiple hard drives, select the external one to make sure that you can boot from it
If this all works. Shut down the Mac, remove the external drive, restart the Mac and update your internal drive to the latest version. Whenever you need to use 10.8.5 again, attach the external drive, reboot your Mac with the Option ⌥ key presses and boot with your external 10.8.5 drive. In the mean time, you internal drive will be at the latest levels.