iMac not finding OS

[mollyc]

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??
[doublepost=1541688895][/doublepost]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.

 

[CoastalOR]

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??

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?

 

[mollyc]

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.

 

[CoastalOR]

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.

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.
[doublepost=1541690482][/doublepost]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.

 

[dwig]

.. I would recommend doing a fresh backup before doing updates.
...

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).

 

[CoastalOR]

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.

 

[mollyc]

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).

I have a bootable clone I did with ChronoSync but it’s several months old. I will make another one.

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.

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.
[doublepost=1541702817][/doublepost]@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?

 

[CoastalOR]

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.
[doublepost=1541702817][/doublepost]@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.

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?

View attachment 802474

Not being bootable is definitely a concern. Check the System Preferences...>Startup Disk to see if the Macintosh HD is a choice.



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

 

[mollyc]

Not being bootable is definitely a concern. Check the System Preferences...>Startup Disk to see if the Macintosh HD is a choice.

View attachment 802477

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

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.

 

[Fishrrman]

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...

 

[mollyc]

@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.