iMac not finding OS

Discussion in 'macOS' started by mollyc, Nov 8, 2018.

  1. mollyc macrumors 68000

    Joined:
    Aug 18, 2016
    #1
    I have a 2017 iMac. Have never had any issues. I am running high Sierra and have not updated to Mojave.

    As of yesterday everything was working properly. At the end of the day I ran an update for Safari, which restarted my computer. After the restart, I shut I down for the evening.

    This morning it will not boot up. It goes through the Apple logo screen (very slowly) and then comes to a page that says the OS could not be installed and I get an installation log screen. I have no idea what any of the log files mean, other than bad news. :(

    I tried safe mode but it just hung on the logo screen with a full bar but never did anything else. I let it try to boot in safe mode for probably 20 minutes and gave up.

    What can I do??
    --- Post Merged, Nov 8, 2018 ---
    Okay, well from the Installer Log page I saw there was an option for Startup Disk, so I clicked that and chose it for Startup, and now I seem to be back to normal?? This is great news, of course, but now what do I do to prevent it from a bad startup next time?

    And now I am going to go make a duplicate backup of all my files. I have them backed up to Time Machine but never quite certain of that.
     
  2. CoastalOR macrumors 68020

    CoastalOR

    Joined:
    Jan 19, 2015
    Location:
    Oregon, USA
    #2
    Try booting to Recovery (command+r at startup). If that works then you can run Disk Utility to check your drive and/or Reinstall the macOS. If that does not work then you may need to try Internet Recovery. I would recommend not having external drives attached to the iMac during the the startup and recovery.
    Do you have any backups?
     
  3. mollyc thread starter macrumors 68000

    Joined:
    Aug 18, 2016
    #3
    Yes, I did remove all peripherals but it didn't make any difference.

    Not sure if you saw my update at the bottom of my post, but I was able to get in through the Startup Disk option on the Installation Log page. I am now logged in as normal. What can I do to prevent this from happening again? Or was it just some sort of one off fluke?

    Since getting back in I ran Disk Utility and it found no errors.

    I will make a new bootable backup; I do have one but it is kind of old, and I am making new backups of my personal data just to be safe. I'm a photographer and the only thing I really care about are the photos on this drive.
     
  4. CoastalOR macrumors 68020

    CoastalOR

    Joined:
    Jan 19, 2015
    Location:
    Oregon, USA
    #4
    You are correct, I was did not see your update. My guess was that it was fluke.

    It looks like you have a good new plan with the backups. Just keep up with the backups. I would recommend doing a fresh backup before doing updates.
    --- Post Merged, Nov 8, 2018 ---
    BTW: See this thread;
    https://forums.macrumors.com/thread...update-2018-002-10-13-6-wont-install.2151143/

    It sounds like what happened to you.
     
  5. dwig macrumors 6502a

    Joined:
    Jan 4, 2015
    Location:
    Key West FL
    #5
    I agree and would add that these "backups" should be full bootable clones created with CarbonCopyCloner or SuperDuper.

    I do these monthly on my iMac at work and ~quarterly on my two print servers that don't really change much. Anytime I have major updates to do, I do an extra bootable clone before the update and then again after the update has been adequately "tested" (read: used for a few days).
     
  6. CoastalOR macrumors 68020

    CoastalOR

    Joined:
    Jan 19, 2015
    Location:
    Oregon, USA
  7. mollyc, Nov 8, 2018
    Last edited: Nov 8, 2018

    mollyc thread starter macrumors 68000

    Joined:
    Aug 18, 2016
    #7
    I have a bootable clone I did with ChronoSync but it’s several months old. I will make another one.

    I usually hold off on updates. Not sure why this one went wonky especially since it looks like it got pulled and reloaded and I used the second version.

    Thanks for the advice. Hopefully a restart tomorrow goes as expected.
    --- Post Merged, Nov 8, 2018 ---
    @dwig and @CoastalOR you both have been really helpful. I have another question. Despite my membership status here, I'm not at all a tech head.

    I am making my new bootable backup through Chronosync. I use this for other drives and backup as well. When I opened the dialog box to update the bootable version, at first it could not find Macintosh HD. I think this is what happened when I started up this morning. I was able manually select Macintosh HD and ChronoSync was happy and started updating the sync.

    So then I went back into Disk Utility and clicked on the i/info button for Macintosh HD and it says in there as Bootable: No. Does this mean when I restart that I am going to have the same issue? I really think the only thing I updated yesterday was Safari and not an OS patch. When I go back into the App Store for updates, it just shows Safari as the recent update.

    ***ETA: Actually the App store is now showing me Security 2018-002 10.13.6, so that wasn't the issue at all.***

    I am now terrified to restart, thinking I'm going to go into the long boot thing (although obviously now I know how to get back where I need to). Shouldn't Macintosh HD show as bootable? Or does that just mean it's not bootable to another machine?


    Screen Shot 2018-11-08 at 1.45.11 PM.jpg
     
  8. CoastalOR macrumors 68020

    CoastalOR

    Joined:
    Jan 19, 2015
    Location:
    Oregon, USA
    #8
    Not being bootable is definitely a concern. Check the System Preferences...>Startup Disk to see if the Macintosh HD is a choice.

    Screen Shot 2018-11-08 at 10.58.46.jpg

    I think you need to backup your data and then reinstall the macOS. Did you try booting to the Recovery Partition (command+r at startup) (mentioned in my first post #2)?
    MacOS Recovery:
    https://support.apple.com/en-us/HT201314
     
  9. mollyc thread starter macrumors 68000

    Joined:
    Aug 18, 2016
    #9
    No, I did not boot into recovery mode because by the time I'd seen that post I had already gotten back in. I have already checked Startup Disk and MHD is an option. Right now I am making my bootable clone and have backed up my photo files. I have a few other backups to make as well before I restart. Thanks for your advice.
     
  10. Fishrrman, Nov 10, 2018
    Last edited: Nov 10, 2018

    Fishrrman macrumors P6

    Fishrrman

    Joined:
    Feb 20, 2009
    #10
    OP:

    You posted above that you tried Chronosync and it didn't work -- is this right?
    If it DID work, ignore the following, but if it didn't, read on...

    I suggest that you try downloading CarbonCopyCloner (or SuperDuper) and repeat with either one of those.

    Both are free to download and try for 30 days -- trying them costs you nothing.

    But don't give up on a "bootable cloned backup" until you've tried CCC and/or SD...
     
  11. mollyc thread starter macrumors 68000

    Joined:
    Aug 18, 2016
    #11
    @Fishrrman No I didn’t need to use ChronoSync. My CS backup was old but I am pretty sure it would have worked. But I was able to specify the boot drive from the Utilities menu. All restarts have worked as expected since then.

    I now have current backups of everything and will more regularly update my bootable clone copy.

    But thank you. :)
     

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10 November 8, 2018