IMac won't boot after upgrade to OS X 10.12.6

[paul_liverpoolfc]

My iMac's a mid-2011 model and, after upgrading from macOS Sierra 10.12.5 to 10.12.6, my iMac now won't boot.

I've tried the upgrade via the App Store and also the Internet but both methods fail.

After booting, the progress bar either gets stuck on 100% or only gets to 75%.

I've also tried installing Mavericks with a bootable USB drive that has worked in the past but I get the installer crash log appear each time. An Internet Recovery installation doesn't work, either.

I can, however, get into OS X by restoring macOS 10.12.5 from a Time Machine backup. It's when I reboot that things go wrong again.

Thanks.

 

[Marcopolo53]

I have iMac 2012 late and had same issue. Discovered ( for me ) there was a ROM updated included in 10.12.6 update. Had to force shutdown, Power Button, and reboot Safe Mode. Took some time to finish but eventually came back to life after rebooting again into Normal Mode.
Good thing u have TM backup. May want to do a Clone too just incase.

 

[paul_liverpoolfc]

For some reason, I can't get into Safe Mode. When I hold down Shift on booting, it just carries on booting normally.

 

[Marcopolo53]

Do u you have a Firmware Password enabled? Do you have FileVault enabled? If either or both, must disable either or both to get into Safe Mode at boot up

 

[joefrank64k]

I had the exact same issue (stuck at 75% progress bar) on a Late 2015 iMac. I tried everything I knew (power-down and restart, safe mode, etc). I eventually called AppleCare, they had me try everything under the sun and they couldn’t fix the issse either. They even had me reinstall Sierra and that didn’t fix the problem. They wanted me to bring my iMac in to the Genius Bar.

I finally tried restoring to an earlier TM backup...iMac booted up normally, no problem at all. So of course I’m leery of installing 10.12.6, haha!! I might wait for 10.12.7 or even High Sierra now.

 

[joefrank64k]

I had the exact same issue (stuck at 75% progress bar) on a Late 2015 iMac. I tried everything I knew (power-down and restart, safe mode, etc). I eventually called AppleCare, they had me try everything under the sun and they couldn’t fix the issse either. They even had me reinstall Sierra and that didn’t fix the problem. They wanted me to bring my iMac in to the Genius Bar.

I finally tried restoring to an earlier TM backup...iMac booted up normally, no problem at all. So of course I’m leery of installing 10.12.6, haha!! I might wait for 10.12.7 or even High Sierra now.

BTW, I used the "Combo" update just now, as suggested in another 10.12.6 thread, and the update went great!! No problems at all. YMMV, etc.

https://support.apple.com/kb/DL1931?locale=en_US

 

[Marcopolo53]

BTW, I used the "Combo" update just now, as suggested in another 10.12.6 thread, and the update went great!! No problems at all. YMMV, etc.

https://support.apple.com/kb/DL1931?locale=en_US

Odd, went from 10.12.5 to 10.12.6 using the combo and that is when I had all the problems. My MacBook Retina 2016 went 10.12.5 to 10.12.6 via Apps Store and zero problems. Here too had ROM update. Seems no pattern.

 

[Pavel F.]

My iMac's a mid-2011 model and, after upgrading from macOS Sierra 10.12.5 to 10.12.6, my iMac now won't boot.

I've tried the upgrade via the App Store and also the Internet but both methods fail.

After booting, the progress bar either gets stuck on 100% or only gets to 75%.

I've also tried installing Mavericks with a bootable USB drive that has worked in the past but I get the installer crash log appear each time. An Internet Recovery installation doesn't work, either.

I can, however, get into OS X by restoring macOS 10.12.5 from a Time Machine backup. It's when I reboot that things go wrong again.

Thanks.

Hi,
the same problem on my MacBook Pro (15-inch, Mid 2010) .
So I restored macOS 10.12.5 from a Time Machine backup.
It is very strange from Apple. Poor Steve Jobs! The honor of his memory

 

[Marcopolo53]

Check for Incompatible third-party kernel extensions. Reading other threads and see similar issue elsewhere. Some have found the boot up hangers because of old, unused, or Incompatible third-party kernel extensions.