IMac 27 Sierra won't log in, or enter safe mode

I have restarted, run disk utility, cleared SMC and NVRAM. I hold down the shift key upon restart (wired keyboard) and it brings me straight to the ordinary log in screen. Any other ideas how to get into safe mode?


When attempting to log into my account, the little white bar goes across the screen, fills up, then actually backs off and freezes. When attempting to go into guest mode, computer freezes upon pressing the "restart" button.

Replies

Same thing. MacBook Pro from 2010

I did a verbose start up. The system seems to have an issue with virtualbox kexts. Will see if I can deinstall them.

I tried to enter verbose mode and got a circle with a line through it in the middle of the screen

I can't even restore the computer from a time machine backup as it's unable to add a recovery system to the disk 😮

That's scary. Do you have anything like virtual box on your mac? I also read somewhere that some virus scanners are also causing this.

I have a Macbook Retina 2016. Installed Sierra. MacBook wouldn't boot, unrecognisable internal SSD... recovery partion worked but would not show up when booted from external drive. The NVMExpress bus to which the SSD is connected showed no devices connected.


The upgrade bricked my macbook. Apple couldn't fix it nor several specialists. It had to have a logic board replacement.


All from an upgrade!


There is a serious serious flaw in the macOS 10.12 upgrade process which can destroy your Mac. Beware.

Maybe a coincidence.


One of my Macs ceased to boot after I toyed with Sierra – flashing question mark, Startup Manager found nothing more than an 'EFI …' option and selecting that one and only option did not cause Recovery OS to start. A reset of NVRAM did not work around the problem.


Happily, the Recovery OS slice was good enough to boot a more modern MacBookPro8,2 with the apparently troublesome older Mac connected via FireWire in target disk mode.


Eventually (I can't recall the details) I found the local Recovery OS (not Sierra Recovery OS) working as expected, so I erased the OS X startup volume and used Recovery OS Time Machine to restore a released version of the OS from a FreeNAS box.


After booting the restored OS, with support for ZFS, use of 'zpool status' found a growing number of errors in a pool that's encrypted with Core Storage. I began a scrub, but soon decided to shutdown the Mac and use something other than OS X to check the drive (SSHD).


I booted from Ultimate Boot CD (UBCD) and used HDAT2 to perform a 'powerful' READ/WRITE/READ/COMPARE test. That test began a few hours ago, it's around sixty-two percent complete and has found no error. I'll review this later …


… in the meantime, I'm reasonably certain that my case was pure coincidence – a disk beginning to fail, in a way that's not detected by the OS, whilst I toyed with Sierra. YMMV.

Can you start in single user mode?


I had that symptom (not specific to Sierra) when attempting to boot from a hard disk drive with USB 2.0. Disconnecting then reconnecting the drive – whilst the no entry sign was on screen – allowed startup to continue. Potentially nerve-wracking, but entertaining.

I can get into single user mode, recovery mode and verbose mode. There aren't any disk errors. I just don't know how to get the thing to work. I can't find the kexts mentioned in the verbose mode, which seems to be the issue. However, I don't know how to get the thing to ignore them during boot up and not being able to get into safe mode makes it harder.

uh oh. Guess I'll try a "bug report" and see if engineering can help. In my experience Apple Store techs in the U.S. won't touch a device running beta software. The strange thing is, I am pretty sure I had removed the computer from my development devices list a while back and it automatically installed the Sierra beta anyway 😠

> … I can get into single user mode, recovery mode and verbose mode. … can't find the kexts mentioned in the verbose mode, …


  1. Take a written note of the names of those KEXTs
  2. boot Recovery OS
  3. use Recovery OS Disk Utility to mount the Sierra startup volume
  4. Quit
  5. use Recovery OS Terminal to browse the mount point and move (set aside) the KEXTs.

Ah ha! I'm not sure if this will fix this for you, but I solved this for me! I was trying to reinstall El Cap on a different drive and ran into this error:


"This copy of the Install OS X El Capitan application can't be verified. It may have been corrupted or tampered with during downloading"


And I googled the solution and it was the system date.


http://apple.stackexchange.com/questions/216730/this-copy-of-the-install-os-x-el-capitan-application-cant-be-verified-it-may-h


I fixed the system date and then had a thought... I wonder if this is my boot up issue.


I put back in the original drive and started it up and "Ah ha!" I was back in business.


I really hope this fixes this for you too!

I posted this yesterday, but as there was a link, it says the post is being moderated, though why it's moderated for over 24hours I don't know...


I'm not sure if this will fix this for you, but I solved this for me! I was trying to reinstall El Capitan on a different drive, so that I could use my computer again and ran into this error:


"This copy of the Install OS X El Capitan application can't be verified. It may have been corrupted or tampered with during downloading"


And I googled the solution and it was the system date. - here's where my link was to the instructions on how to change the system date when in restore mode via the terminal.


I fixed the system date and then had a thought... I wonder if this is my boot up issue. I put back in the original drive and started it up and "Ah ha!" I was back in business.


I really hope this fixes this for you too!

I'm curious to what you mean there...to my knowledge there's not an "automatic" upgrade to Sierra for Macs...you have to redeem the code in the App Store and download the installer & run it. The iOS-derived versions all have to be registered in the portal to run the betas and you must install the newer Developer Configuration profile...but I've never seen or even read about a Mac doing this. The Downloads page only gives you the code needed and clicking the Download button launches the Mac App Store where you must redeem the code.


The 1st developer version of any major OS X (of course now macOS) has always been a full installer download. Once the OS is released final, they offer the Seed Configuration Utility that flips the settings in Software Update to allow for beta builds, but those are always minor releases for the same major point version (10.10.x, 10.11.x) and not for a major to major upgrade.


If they follow the same pattern as past years, beta 5 or 6 may be another full installer and not a delta/combo "update" since they put a lot larger code change in it...

nope date on my computer is correct.