iMac not booting after upgrade to Yosemite

What version of OS X was installable before Yosemite, if it was Lion to Mavericks then boot into the recovery partition and restore from a TM backup. When posting please provide useful information such as what version of OS X was installed, what iMac you have, how much available disk space, the amount of RAM installed etc...

Yosemite: boot hangs at 50% percent

You should maybe be able to get into internet recovery and try to repair or repartition (with data loss) the disk

OS X: About OS X Recovery

Did you reset the NVRAM?

I manage one of the biggest call centers in the world and use iMacs and would like to share this helpful work around for all new Yosemite users, hope this helps & good luck

1. Unplug the Ethernet cable or disable the WiFi
2. Unplug the power cord or battery, wait 25-30 seconds for power to drain/clear and then boot up unit, the OS should load after this..

Thanks, Roy, turning it off and on again did the trick! 🙂

My previous post was a work around for at home/personal users which should work, the OS try's to retrieve user authentication Info from the previous logged on user so disconnecting the network cable or disabling or turning off the WiFi/ wireless should do the trick. For all those Domain Admins/Users enable do not write on the users directory so the OS doesn't recognize a user account to try and retrieve info, if you perform this the OS will just create a temp user profile folder and delete it when theirs a power failure and not try to look for it after the power failure when booting up not causing to give you the gray boot up splash screen and go right into OS X, hope this helps and good luck!

Detailed work around for at home/personal users which should work,disconnect the network cable or disable / turn off the WiFi / wireless and then reboot the computer. Make sure to leave the power cord and battery of for 25-30 so the power drains before you boot back up this should do the trick.

For all those Domain Admins/Users, enable do not write on the users directory so the OS doesn't force a local directory on the startup disc and try's to retrieve info. If you perform this the OS will just create a temp user directory profile folder and delete it when a power failure or reboot occurs and doesn't look for it after the power failure or reboot when booting up and not give users the gray boot up splash screen with progress bar and go right into OS X, hope this helps and good luck!

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.

Hi,

Thanks so much for posting this very helpful information. I am going to give it a shot.

My experience was similar - the mac wouldn't boot at home, but it would boot just fine at work. Resetting the PRAM would often get me going - if I my next login was with the network unplugged.

A couple of quick questions.:

1) Would you recommend that this issue be reported to Apple as a bug?

2) Do you happen to know if this is just an artifact of "upgrades" to Yosemite (i.e., clean installs work ok)? Or, is there an underlying issue with Yosemite on Active Directory Domains for all machines (old / new alike) when they are booted away from the domain?

Thanks in advance...

If you have Mcafee try removing it. I was told by Apple Help that some versions of Mcafee are not compatible with Yosemite. I removed it and my iMac is starting up ok now.

I have the same problem. I tried this but did not work for me. I agree it has to do with active directory. It works when when connected to the network. When I take it home and restart the computer it starts to hang. Anyone has found any other solution?

Are you ready for my 2 cents? I, too, am frustrated by this issue. It has popped up on about 20% of the machines I have updated here at the high school (about 50 or so). Our Macs authenticate to Win 2008 server running Active Directory & use OS X Server for management.

I updated a couple of Mac Airs to Yosemite & it looked good. The update solved a Mavericks problem with the login sticking at "Updating Managed settings" for at least a minute-- that's a problem when a whole class are needing to get rolling! Under Yosemite, the login is very fast for the Macs that are working properly, but oh those "stickers!" The Macs that stick will not go beyond the progress bar screen. This is for Macs that are bound to AD & connected to our network & it happens both for wired & wireless connections (MacBook Air and iMacs).

I've had success running Disk Utility & Disk Warrior on some of the afflicted machines. (Put the "patient" in Target mode & connect it to a Mac with the diagnostic software installed via Thunderbolt cable.) Those are now running OK with Yosemite. But there are others that I had to roll back to Mavericks using our Apple server's Net Install feature. (You could also do a System Restore by starting the Mac while holding ⌘-R)

I don't recommend binding client machines to AD without forcing the Home directory on the local disk. That will put the user's Home on the network, which creates other problems due to a lot of writing back & forth across the network (i.e. it hogs your bandwidth & can cause corruption).

I reported the problem to Apple a few days ago. Ultimately, the "fix" will probably be a 10.10.1 update.

10.10.1 doesn't fix it. any time you hard shutdown a yosemite machine bound to Active Directory (whether on the network or not) it won't boot when you turn it back on. You can do Command V to watch where it sticks at boot. Turn it off, unplug for at least 30 seconds, turn back on and it should boot.

I just created a script to remove Screen locking from all users to avoid the scenario where a student forgets to log off and the teacher does a hard power cycle to let the next student log in.