iMac not booting after upgrade to Yosemite

FWIW -- these steps:

Once you have booted the unit up successfully perform the following below.

Step 1 Open System Preferences and select Users & Groups

Step 2 Select Login Options

Step 3 Select Edit on the network account server button/section

Step 4 Select Open Directory Utility

Step 5 Select Active Directory

Step 6 Select small gray arrow pointing to the right on the left side to collapse

Step 7 uncheck Force local home directory on startup disk and then select the OK button.

Made no difference here. The test laptop I tried with clearly *does* freeze at 40-50% of the progress bar -- *if* the laptop is bound to AD.

But unchecking that box did not make any difference the next time I did a hard shutdown. It still froze up.

I haven't found one sure-fire method of bringing a laptop back to life when it's in this state. PRAM zaps -- are not consistent. Single user booting to remove /Library/Preferences/SystemConfiguration/* -- no different. Power off, unplug power cable/network cable for 30 seconds and reboot -- doesn't matter.

"Safe Mode" booting seems to be the only thing that's more consistent than others, though.

But if I unbind from AD, I can hard power down and boot up normally all I want.

If you are having this problem, please file a bug with Apple. It's a pretty critical bug, IMO. It can render a computer useless and an end-user would just keep rebooting the system over and over with no success. Or with magical success after some special boot that eventually seems to work.

I agree Steve, it is a pretty serious bug. Thanks for replicating.

It's been over 2 weeks since I first reported it to Enterprise support. Today they finally told me I could work directly with engineering in this follow-up email I received:

"We have been able to provide an exception on this case to allow you to work directly with engineering on the issue.

You should be contacted shortly by someone from our engineering team to keep this moving.

There may be some delay due to the holiday week, but I do know that an exception has been approved."

I wonder if "exception" is Apple code for accepting that a bug really exists AND some desire to fix it!

Hopefully I hear from someone in engineering within a few days...

Yeah, we've purchased AppleCare Technical Support for our University, so we are working with somebody as well -- but we just flagged this ticket yesterday...

But I'm finding that even Safe Boot doesn't work every time, either. There's no "one size fits all" fix for this. Yuck.

I've been keeping track of this in our labs at the high school by writing down the number of the machines that are hanging at boot and noting how I fixed them. I had a repeat offender this morning and ran Disk Warrior again which fixed it. So the fix only lasted a few days in that case. Since DW repairs errors in the drive's directory structure, that would seem to be the problem area.

I sent an email to Sandy Brenner, one of Apple's system engineers, this morning.

FWIW -- I asked the Apple Support Engineer working on my case if he could reproduce this on his end with his AD set up -- and he could.

So my guess is this will pick up traction pretty quickly since the problem is not specific to our AD configuration (which is good...)

But that doesn't mean you shouldn't file a bug if you haven't!!!

So, this is not necessarily a "fix" -- but a potential way to get back up and running.

Boot into Single-User mode

and mount the drive with:

/sbin/mount -uw /

Then delete this directory:

rm -rf /Library/Preferences/OpenDirectory

then "reboot".

This, of course, unbinds the computer from Active Directory. So it's not going to work for everybody.

It works for us as our managed machines will rebind a machine to AD automatically if it becomes unbound for some reason (when an hourly script is run on the managed machines.)

Out of everything I've tested (PRAM zap, safe boot, etc.) -- since the problem seems to be specific to machines bound to AD -- removing the AD configuration in single user mode may be the only "sure-fire" way around this issue (until Apple fixes it.). We've tested machines where the PRAM zap/Safe Boot has to be run multiple times to make it work and no amount of multiple-just plain-reboots (which seems like it can work eventually on most computers) was working

YMMV, of course... If you don't have a way to automatically rebind machines to AD, you'd then have to manually rebind them. (And, obviously, this solution a serious pain for a managed lab, of course where you can't single-user boot remotely...)

My wife and I are both faculty at a major university, which uses AD and university-approved disk images. My wife, currently traveling FAR outside of the US, just got hit with the "hang at boot" bug after a power brownout forced her 2013 13" MBA to restart. Trying to troubleshoot over FaceTime and over a 12-hour time differential is a challenge, but these tips certainly look useful. Not entirely sure the image will allow her to boot into Single User mode and follow the instructions above, but it's worth a try.

FWIW, our university's solution to this issue: bring the computer (or have it taken in, if a desktop) to ITS for re-imaging back to Mavericks.

Wanted to drop you all a line and say that Steve's fix DID in fact work for my wife's MBA, which I successfully troubleshot from 10,000 miles away via FaceTime 😎. Once I have it in hand I'll work through deeper fixes (if needed). I really don't want to hand it off to tech support to re-image back to Mavericks. Yosemite has some pretty nice features that would be a shame to give up.

I want to clarify that this is a fix we experimented with and figured out internally. It is not an officially-supported fix from any other other source.

Just wanted to make that clear to all concerned.

No worries! Everyone knows that there are no "official" fixes anywhere on these boards. Definitely the best (and worst) of crowd-sourcing solutions. I will say that for my part, it saved a LOT of aggravation, and official or no, it's a good solution.

Has anyone checked to see if 10.10.2 beta fixes this issue? Every time my son comes home from school I need to unbind the Domain in order to eliminate the hangs/wagon wheel syndrome. I've also noticed that the issue is more apparent when File vault is enabled.

Any info would be appreciated!

Joboo77777 wrote:

Has anyone checked to see if 10.10.2 beta fixes this issue? Every time my son comes home from school I need to unbind the Domain in order to eliminate the hangs/wagon wheel syndrome. I've also noticed that the issue is more apparent when File vault is enabled.

Any info would be appreciated!

NEVER EVER upgrade to a new version of an operating system to solve a problem. Doing so in almost every case makes the problem even more difficult to resolve!!! Continue working to find the solution, once you have and your system is working perfectly then perform any updates or upgrades.

Not sure there is much more troubleshooting that can be done until Apple provides some direction on the issue. I'm simply asking those with access to 10.10.2 beta to provide feedback on whether it addresses the issue described in this thread(particularly around Domain Joined Macs).

Thanks

Issue seems to be getting worse on worse on the iMac in my lab. Happening more and more frequently and none of the proposed fixes in this thread work every time. Seems to be a different one that works each time.

And it actually sounds like this has been a problem since the beta, judging from this thread on macrumors: http://forums.macrumors.com/showthread.php?t=1747268

Hi Steve,

Just curious if you have had any updates from your Apple contact since you posted originally around the first of December?