Yosemite: boot hangs at 50% percent

AAny joy with this? My MacBook pro hangs at just under 50% was working perfectly yesterday.

I have tried all the suggestions and now the iMac progress gets about half way then shuts down

I think you would get a better response if you started a new thread as the iMac shutting down wasn't part of the OPs problem.

I had Yosemite also hang at 50% after I had Finder freeze up and forced a hard reset. It came back up and I copied some files and then shut down my Macbook Air. The next morning the hanging occurred when I tried to start. Resetting the PRAM didn't work, but resetting the SMC did. The basic cause seems to be some corruption occurring in SMC or PRAM, but the cause of the corruption could be any of the thing already mentioned and more.

We are having the same problem which started happening on one iMac 27'' bought in 2013 and now another second exactly the same iMac doing the same.

The way to boot is to do hard switch off, then boot with CMD+R, go to Disk Utility then:

Verify Permission -> Repair Permissions

Verify Disk -> Repair Disk

Restart

it then boots within about 1 or 2 minutes.

Two or three days later - exactly the same issue, iMacs wouldn't boot with progress bar stuck around 50%.

Repeating the above disk "repair" allows to boot but again only for couple of days.

This has never happened with Mavericks, started happening few days after upgrade to Yosemite.

Both iMacs have standard 1Tb HDD not SSD, but are connected to Active Directory, which one of the comments suggested could be something to do with this but I cannot find the answer how AD affects this...

Can someone help with resolving the problem?

EG TECH we are having an identical issue. Very frustrating - we run an environment with 350 macs - many machines are stuck. Apple suggested to one of our techs that the new release (10.10.1) would solve this issue. Apparently, it does not.

HI all,

SAME ISSUE Here. Have been struggling with this for a month now. NEVER had this issue with Mavericks or lion but now sure enough OFTEN the progress bar at boot up freezes and at different times my patience has allowed me to wait for up to 2 hours only to come back to the bar being stuck in the same spot.

sometimes I reset the Pram or do a restore boot and am able to repair disk permissions but sometimes that doesn't even work and I'm stuck hard cutting the power only to try again. This is VERY lame. Had I known it was going to be this much of a pain in the *** and bring such serious down time I would have dodged the Yosemite update altogether. But suffice to say I naivery jumped on board the first day Yosemite went public.

Lastly, I have to add that I've broken down to doing both a full system restore from a backup of time machine which took about 4 hours and previously to that I reinstalled the Osx which took about 1-11/2 hours. And after still had problems. I've messed with this issue now for a month and there is no fix in sight, and even now I'm looking at a progress bar that's been stuck at halfway for quite a while Which means yet another hard reset and more messing with reinstalls.

I Mean I know I'm running a late 2009 so 5 years old is ancient these days but still. At least put a warning in the Yosemite update? And it sounds like some 2013 models are having this issue too so idk I'm not an apple employee, but if I were I'd do my jon and help people like me who rave about how good the products are.

ok I feel a little better and if anyone has a definite fix on this freezing at 50 percent Yosemite thing please let me(the world) know ASAP! The pram isn't it 😉

Reset the SMC MacBook Air SMC and PRAM reset

Resetting the SMC worked for a late 2012 iMac 21.5 running Yosemite

Great, finally!

This one worked for me (although I had reset the PRAM first, with no success. I just had to reset the SMC and perfect result

Thanks!!

Ok, for me, I booted into recovery mode (Cmd-r) and was able to run disk utility.

It ran fine for the volume, but when I cliced on the "iMac HardDrive" that's when I had issues.

Verifying Volume: This disk needs to be repaired. Click Repair Disk.

Then: Disk Utility cant repair this disk….disk, and restore your backed-up files.

I'm reformatting now. So glad I have a time machine backup!

Thanks, so what do you do with that many Macs to resolve this?

We've got 3 having the problem and had enough of running disk repair every 2-3 days!

Is there ever going to be a solution, does anyone know?

Hi there,

I have the same problem. I have an iMac 2010 27" and a MacBook Air Mid 2012.

MacBook Air works perfectly with 10.10.1. FileVault is enabled and never had an issue with any of the updates to Yosemite.

Right now I have that problem with my iMac, it hangs at 50% of the progress after reboot.

With the first update to Yosemite, my iMac worked just fine. Before doing this update, I erase the hard drive and reinstall Mavericks from Internet Install. Then I update to Yosemite and everything was fine. Then, I had the advice from a friend to use FileVault to protect info of the hard drive. So I went home and activated the FileVault encryption. There was when everything started to failed.

The iMac started to run very slow, it took me a lot of time to make any movement on OS. One of the things I remember I did, was to turn off the option of "sleep hard drive" or something like that. And the option of turn off the screen, I configured it to happen after 3 hours. I thought that encryption will take time and I had to be patient. I also thought that if Hard Drives go to sleep often, the process maybe slower, so that is why I turned off this option. Other thing I did, was trying to update to 10.10.1 because I thought that would solve the problem. But I couldn't did it because the system showed an Error when I tried it. So I let go this option.

My iMac was like this like for 3 weeks with no progress in the encryption status bar, in the "System Preferences" window. Was that moment when I decided to turn of FileVault, but it wasn't possible, I had to wait to the encryption progress finish to be able to perform this action. So I searched in some web sites and I found a way to deactivate FileVault from Disk Utility. So I did it and everything came to normal. I was happy.

After that, as I thought everything was normal again, I was happy to be able to update to 10.10.1 finally, so I did it. Worst mistake ever...

First thing I experienced was that the iMac hanged at the gray screen for several hours (more than 24) and the colored spinning wheel. So I decided to erase hard drive and reinstall, anyway I had no much information to lost, everything was manually backed up because I did it when I format the iMac when I had Mavericks.

So I format, reinstall, but nothing happened, now with this issue of the 50% progress status bar. I let it for more than 24 hours but didn't work. Since then I have tried several things like:

Force reboot, but the problem remains.

Erasing/format disk and reinstall Yosemite from USB bootable drive and but the same problem remains.

Tried to Start in Safe Mode, but iMac seems not to recognize Bluetooth Keyboard so Shift function is not available. So I plugged a wireless USB non Mac keyboard, but Shift option still not working.

Tried to start in Safe Mode from Terminal starting from Recovery Mode, but when I hit the command to program start up with Safe Mode, Terminal displays a message telling me that the command wasn't found.

Right now I am repairing disk permissions for the second time (is taking hours) and after that I will try to repair disk, but when I tried to repair disk for the first time, an Error displayed telling me that the disk wasn't able to unmount disk. So, I hope that after repairing disk permissions I will be able to repair disk. After that I will reboot and wait for the best. If it doesn't work, I think I will wait for a new update or reinstall Mavericks or I don't know. I have read that reseting SMC and PRAM works. But I already restart PRAM when I activate FileVault and I think that the SMC option is not available for the iMac. Right now I am very desperate, I have being battling with this problem for almost two months. It is consuming my time at that grade that I am not doing my job.

So, I hope you are reading this, Apple.

Apple doesn’t routinely monitor the discussions. These are mostly user to user discussions.

Send Apple feedback. They won't answer, but at least will know there is a problem. If enough people send feedback, it may get the problem solved sooner.

Feedback

Or you can use your Apple ID to register with this site and go the Apple BugReporter. Supposedly you will get an answer if you submit feedback.

Feedback via Apple Developer

Hi Eric,

Thanks for your answer. I know Apple doesn't read this.

Cheers!

Just an update...

My iMac just finished repairing permissions and after that, I repair the disk.

Register said that the Disk seems to be ok.

So, I am rebooting right now, waiting to se what happen. Until now, I don't see any type of improvement or change in the way the progress bar moves.