Get out of OS upgrade installer on restart?

Solution 1:

I wrote a blog post on some options, and you should be able to boot to your Recovery HD and re-install some OS X onto an external drive. You could also try to re-instal the OS on top of the current drive as that's not designed to delete anything important and might just work to painlessly repair things.

• http://apple.blogoverflow.com/2015/09/back-up-then-step-up-to-el-capitan/
• http://apple.com/osx/recovery

Without knowing how proficient you are with more advanced install options, installing even on to a 16 GB USB flash drive would get you to a place to re-run the correct installer and try again with the upgrade. From the second link:

If you use the Recovery System stored on your startup drive to reinstall OS X, it installs the most recent version of OS X previously installed on this computer

Solution 2:

Try holding the Option key on restart (once you hear the boot chime) until images of hard drives appear, then choose your hard drive from the list, it's default name is "Macintosh HD", but you may have renamed it. Boot into it by pressing enter.

If that doesn't work, hold down the power button until the Mac is off, then turn it back on and repeat the above answer.

Solution 3:

I almost gave up on my hard drive and almost wiped it clean.

Background: I upgraded the archaic spin drive to a 1tb SSD in 2013 iMac months ago. Something possessed me last night to hit upgrade to High Sierra.

The download went fine but when I said install the computer got stuck in the loop, of can't install the update because "your computer file system verify or repair failed" and no matter what I did I could not get out of this loop. I tried to boot form recover, boot form USB with sierra installer, tried to repair the hard drive which gave me errors like File system check exit code is 8, I tried single user mode, I tried network recovery..... like I said I tried everything. My plan was to dig up the old spinning hard drive to restore an image form it, albeit it few months old but better than nothing. Of course I do not have a backup because I said to myself this is an SSD on a mac what could go wrong, well I learned that lesson. Bottom line what needed to happen was enable journaling of the hard drive, something that was greyed out and was impossible to do. Installing a fresh OS was also not working because the computer would say the drive is locked. Enough of the problem here is the solution.

I bought a thunderbolt cable to connect the iMac to my trusted MacBook Pro. I then installed Disk Warrior software on a MacBook pro. Then I booted the iMac while holding down the t key, which allowed the MacBook to see the iMac as an external drive. Disk Warrior scanned the iMac's hard drive, rebuilt its directory and enabled journaling. I then unmounted the iMac from the MacBook and rebooted the iMac normally, and viola, high Sierra installation proceeded and 40 minutes later I am back to normal. I am considering this post and pay back for all the help I got from searching the net for hours on this issues.