Yosemite: boot hangs at 50% percent

This has worked for our work computers....

Boot in safe mode, once you are in there, click on Macintosh HD (or whatever your hard drive is called), Library, and find LaunchAgents and LaunchDaemons. Make 2 folders on your desktop and copy all of the files from each folder and place them in one of the corresponding folders you created on your desktop. Once you have copied those files into the folders, choose all of the files from the Library folders and trash them. Empty your trash and then restart the computer. The computer should then boot normally after the restart.

I hope this helps.

Thanks @waterstarheel

It worked for me to thrash those files. Now let's see for how long my MacBook Air (mid 2012) stays up and running. OS 10.10.3

I should maybe also say that I before this tried all the basic stuff like pram and just restarting many times.

And I also did both step 1 and 2 as Banks suggests here https://www.afp548.com/2015/01/14/when-yosemite-has-fallen-and-it-cant-get-up

What do you people who know more about why this happens to Macs in the first place suggest I do now? Just keep running it or replace the HD or other hardware?

Thanks,

Johan

Following worked for me nicely without any hiccups

• Shut down your Mac and wait 10 seconds.
• Press the power button.
• Immediately after you hear the startup tone, hold down the Shift key.You should press the Shift key as soon as possible after you hear the startup tone, but not before.
• Release the Shift key when you see the gray Apple logo and progress indicator (spinning gear).
• Once you Mac boots into Safe mode restart it to normal mode.

We updated our 2008/2009 iMacs at our School district to 10.10.3 and now all boot normally AND the WiFi (seeing double SSIDs) issue is gone. So happy to have them back in working order again.

Something similar for me worked. We have iMAC mid 2011 at our school on Active Directory. The one loaded recently with Yosemite was hanging at 50% for some reason on startup.

The following worked for me:

Power iMAC off. Turn it on HOLD the COMMAND + S key down(Booting Single User mode), type exit once you get to the command line, it should boot into OSX. Shutdown/Restart it again to see if it boots normally.

OK, I've just come to the conclusion that I've not been victim of the same problem as the rest of you describe, however, the result of my problem has been the same - hang at 50%.

Turned out to be my login hook. Sure, it's been deprecated for a long time now, but it seem that in Yosemite it is not stable at all. Anyone using login hook on Yosemite and have it working under 10.10.3? I will continue testing later, but most likely I have to abandon it.

If you have the hang at boot and also using a login hook - remove it and the your computer will start up just fine.

We have a brand new mac pro at work that shipped with Yosemite. We DID NOT want Yosemite.

We've had it 10 days. I installed some apps and set up some printers. Today I've got the 50% hang. I can't boot in single-user, safe mode, or recovery mode.

I know I had issues with auto-login and turned off file vault last week. What's next?

Hi all,

I have been dealing with the log-in process hanging at ~50% for almost a week and the problem now seems to be rectified. Hopefully my experience is helpful for others in similar situations.

• I don't ever recall using FileVault. On account of that I disregarded the FileVault 'solutions' in this thread. What I've since learned (after the fact) is that during the Yosemite upgrade process, FileVault defaults to the 'on' position. As it turns out, this is important information to consider.

• After a few days trying to get past 50% login and getting nowhere, I became frustrated and began the process to reinstall the operating system from scratch (which I was trying to avoid). Before attempting that, I put my affected MacBook Air (MBA) into Target Disk Mode and used a Thunderbolt cable to connect my MBA to another machine in order to copy contents from my affected MBA's desktop that I created since my last Time Machine back-up. I expected my MBA's HDD to appear on the desktop of the host computer. It didn't. Then from the host computer, in System Preferences I attempted to change the Startup Disk to my MBA's HDD. If successful, the contents of my MBA would load from this host computer and I could perform one last backup before creating a new partition and completing a fresh Yosemite installation. The good news is that my affected MBA's HDD was an available Startup Disk option, yay. When I selected my MBA HDD to be the Startup Disk on the host computer, the host computer prompted me for my administrator's password to turn-off FileVault on my MBA (this caught me off guard because I hadn't recalled ever turning-on FileVault). Upon entering my MBA's administrator password, the host computer immediately crashed. I tried this a few times with the same result. Thinking I'd hit a brick wall, I tried to back-up the recently created content on the desktop of my MBA using Terminal.

• On my MBA, I started-up into Recovery Mode and used Terminal to manually copy the contents of my desktop from my MBA to an external hard drive connected via Thunderbolt. These are the Terminal commands I used that you may find useful:

ls /Volumes (this command lists the volumes accessible in Terminal, mine were 'Macintosh HD and my external hard drive called 3TB)

cd /Volumes/Macintosh\ HD/Users/johngunter/Desktop (this command changes my current directory to the desktop in my user account)

ls (this command lists the files and folders on my desktop)

cp -R Desktop /Volumes/3TB (this command performs a recursive copy - i.e. files, folders and contents of folders - from my desktop to my external HDD)

• After successfully backing-up the contents of my desktop and knowing I had a recent Time Machine backup of everything else, I was confident beginning an operating system reinstallation, which I was able to initiate from Recovery Mode. At the stage to select the destination disk for the OS installation, I should have been able to select my local HDD, however it wasn't presented as an option. In fact, no destination disks appeared as options. Befuddled, I walked away from the process for a few minutes.

• When I came back to the machine 20mins later, for whatever reason, I restarted my MBA and logged-in expecting the process to hang at ~50% and for me to stare at that for while thinking of my next move. Instead, the login-in process completed and I was logged-in!! Success!! Suspicious, I opened System Preferences to check FileVault and it indicated that the FileVault-turn-off process was halfway done and needed another 20mins to complete. I let that process finish, performed a TimeMachine back-up, updated my operating system to the latest version (I had missed an update in the last week), performed another TimeMachine back-up and held my breath as I restarted my MBA. I managed to login again and for the last 24 hours, am no longer experiencing the 50% hang-up.

• Since not being able to get past 50% during log-in for a number of days, the last setting I changed on my affected MacBook Air before being able to fully login was that I remotely switched-off FileVault. Take it for what's it's worth, that's what worked for me.

So there you go. I hope that helps.

I'm going to try again today to boot in Recovery Mode and reinstall the system, then do the upgrade. If it doesn't work I'll have someone take it to the Genius Bar. We've only had this unit for 2 weeks.

Currently I am not able to boot at all. Not safe mode, single user, or Recovery Mode. I've tried unplugging it for awhile, but nothing is working. Makes it impossible to troubleshoot here.

I managed to get this unit to boot using online support. My mouse and keyboard were plugged into the thunderbolt display. I moved them to be plugged into the mac. Boot still failed. I moved the thunderbolt plug to the other side of the mac and it booted. The computer has all kinds of permissions issues and apps failing. I am now attempting to do a fresh install of the system, then will update to 10.10.3.

I've tried all these methods listed above and no one works for my macbook pro, to conclude upgrading yosemite broke the mac , so i'll never buy any apple products again. What kind of apple support is that where fruit-team ******** are not even able to solve such a common problem 😠

Hi everybody,

This thread has been of great help. I have a Macbook Pro Early 2011, 16 Gb RAM (upgraded from 4 GB), 2.3 Ghz i5, 320 GB HDD running on Mac OS X Lion (I'm sorry I forgot to note down the exact version, I think it was 10.7.3). I did the following steps:

1. Open Disk Utility; select HDD.
2. Run Verify Disk. If errors, run Repair Disk.
3. Verify Disk Permissions. If errors, run Repair Disk Permissions.
4. Then download OSX Yosemite from the App Store. Run the installation, restart, and the reboot gets stuck at 50%.
5. Hold down power button for manual shutdown. And then restart the laptop after 30 seconds.
6. Press cmd+R so it starts up in safe-mode.
7. Choose Disk Utility and re-do steps 2 and 3. This will take a time, be patient! (for me mostly printer related stuff in Disk Permission Repair)
8. After step 7 is done, choose Install OS X. It will start another download.
9. After the download is done, run the installation, and it will reboot completely.

After Yosemite started working, first thing I did was run steps 2 and 3 again to be sure the HDD was in order. Again have patience for this part. Disk permissions repairs had to be done, but no disk repair. I shut off the laptop and restarted it 3 times. No problems and pretty quick boot.

Two important points in my software simpleton opinion: Make sure you have at least 8 GB RAM so Yosemite has enough memory to work with, I invested in 16 GB RAM upgrade coming from 4 GB. And make sure you have a backup of your previous OS. That really saved me, as it took me four attempts to finally get the right method for me.

Hope this helps someone.

im not able to get it in safe mode

Did you keep pressing CMD+R? Or did you just press it once? I kept pressing it until safe mode started.

What kind of model do you have? iMac, Macbook air/pro, etcetera?

From what OS do you come? Lion, Mountain Lion, Mavericks?

I have the CMD+R open. I have a iMac with Mountain Lion.