DlacVal
Level 1 (1 points)

Q: Yosemite: boot hangs at 50% percent

Hi,

 

we have a lot of iMacs hanging at boot since the update from Mavericks to Yosemite.

They are stuck at 50% on the progress bar.

 

All discussions we have found about it say that this is caused by TRIM on SSD devices, and that we must disable TRIM.

But all our iMacs are HDD, so this solution doesn't apply.

 

This seems to workaround the problem for us:

 

Reset NVRAM with  CMD+ALT+P+R

Then boot in safe mode, http://support.apple.com/kb/ph14204

Then reboot normally.

 

I hope this helps people who get the same problem.

iMac, OS X Mavericks (10.9)

Posted on Oct 18, 2014 10:46 AM

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DlacVal

Q: Yosemite: boot hangs at 50% percent

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  • by TXBrit,Helpful

    TXBrit TXBrit Oct 18, 2014 9:08 PM in response to DlacVal
    Level 1 (5 points)
    Oct 18, 2014 9:08 PM in response to DlacVal

    Worked for me !  Though I didn't bother with the safe boot mode but went straight to normal. Many thx

  • by L1C,

    L1C L1C Oct 20, 2014 6:49 AM in response to DlacVal
    Level 1 (0 points)
    Oct 20, 2014 6:49 AM in response to DlacVal

    Hi,

     

    I have got the same problem. Could you elaborate more about what you did?

    I mean , if the system is stuck you cannot reset NVRAM..

    SO did you do a NVRM reset before the update? Or did you do it after a reboot?

    And now, does your imac still show a progress bar during boottime?

     

    I just rebooted the imac, it works fine, but I still got a progress bar under the apple logo and boot takes 3 minutes…..

     

    Thanks for your help!

     

    Leen

  • by TXBrit,

    TXBrit TXBrit Oct 20, 2014 6:59 AM in response to L1C
    Level 1 (5 points)
    Oct 20, 2014 6:59 AM in response to L1C

    When the system is "stuck" hold the power button down  until it shutdown and then reboot resetting NVRAM (never did this before installing Yosemite).  From what I read on here its normal now in Yosemite for the progress bar to show during boot sequence.

     

    I still have problems when I leave the iMac for a period of time even though I have the "Never Sleep" option set. The machine just hangs so I have to reboot. It always takes a minimum of 2 reboot attempts to get going. Generally if it hasn't gotten to the login screen within 75 secs it means it neve will so I just reboot again until it does

     

    Also on more than 2 occasions while working the iMac has just hung.  In the process of trying to work out why:  I have removed all startup programs and uninstalled a few add ons that appeared at the bottom of system preferences like OSXFuse. I was also using Chrome when it went both times so just in case am now using Safari exclusively

  • by DlacVal,

    DlacVal DlacVal Oct 20, 2014 9:45 AM in response to TXBrit
    Level 1 (1 points)
    Oct 20, 2014 9:45 AM in response to TXBrit

    Hi,

     

      A few iMacs stubbornly refuse to boot, even with the reset NVRAM and safe mode.

    I managed to boot one of these iMacs like this (I'm waiting for the next one to confirm it works):

     

    Boot in single mode (Mac OS X: How to start up in single-user or verbose mode)

    Type the command "nvram -p", and here something strange is displayed: there are only 2  lines -

      display-config %00%00%%01s%08%ff%ff%01%00

      backlight-level %fa5

     

    Reset NVRAM (OS X Mavericks: Reset your computer’s PRAM)

    Boot in Recovery Mode (OS X: About OS X Recovery)

    Open Disk Utility, but in my case, DIsk Utility found no errors on the Volume

     

    Open Terminal

    Type the command "mount" to display the volumes. In my case I'm interested by this line:

    /dev/disk2s1 on /Volumes/Macintosh HD

     

    Then type this command:

    bless --device /dev/disk2s1 --setBoot

     

    Then reboot. If all is well, it should reboot normally.

  • by L1C,

    L1C L1C Oct 20, 2014 10:08 AM in response to DlacVal
    Level 1 (0 points)
    Oct 20, 2014 10:08 AM in response to DlacVal

    I tried our advice. No change. Te system reboots, but the progress bar takes something like 55 seconds after the chime to fill before the login appears. I Can live with that, but is it normal?

  • by Old Toad,

    Old Toad Old Toad Oct 20, 2014 10:11 AM in response to L1C
    Level 10 (141,085 points)
    Mac OS X
    Oct 20, 2014 10:11 AM in response to L1C

    Boot into the Recovery volume (boot with the Command + R keys held down), select Disk Utility and repair both the disk permissions and disk.  Reboot normally and see if there's any improvement.

     

    If not I'd reboot into the Recovery volume and reinstall the system.

    OTsig.png

  • by DlacVal,

    DlacVal DlacVal Oct 20, 2014 10:12 AM in response to L1C
    Level 1 (1 points)
    Oct 20, 2014 10:12 AM in response to L1C

    I'm not trying to make the boot faster. My problem is that some iMacs hang at boot, even if I wait 30 minutes, they stay stuck at 50% of the progression bar.

  • by L1C,

    L1C L1C Oct 20, 2014 10:52 AM in response to DlacVal
    Level 1 (0 points)
    Oct 20, 2014 10:52 AM in response to DlacVal

    TThat was exactly my first issue too. I solved it by pressing the power button twice to reboot it. As simple as that.

     

    anyhow, iT boots. I Will wait for THE next fix level. Should come soon :-)

  • by IUnderwood,

    IUnderwood IUnderwood Oct 23, 2014 6:03 AM in response to DlacVal
    Level 1 (0 points)
    Oct 23, 2014 6:03 AM in response to DlacVal

    I've had the same problem.  I thought it was a lot of things, actually:  FileVault, Screen Saver, Login Keychain, etc.  Looking at the TRIM settings and such with my SSD was a non-issue as the TRIM support was disabled on my drive with 10.10.  I've been trying lots of different settings on the Mac to see if there was one which would make it stop misbehaving as Mavericks worked wonderfully.

     

    While pondering this, the errors, hangs, and whatnot do look suspiciously like a drive issue and I thought the problem might be HDD hibernation since the manifestations seem consistent with a drive on the way out.  I turned this off and have been running pretty smoothly.

     

    Under Preferences -> Energy Saver, uncheck "put hard disks to sleep when possible."

     

    I wonder if this will work for more people than I.

     

    FWIW, I have an early 2011 MBP (MacBookPro8,1)

  • by L1C,

    L1C L1C Oct 23, 2014 11:24 PM in response to IUnderwood
    Level 1 (0 points)
    Oct 23, 2014 11:24 PM in response to IUnderwood

    it looked promising, i had also hibernation on, boot the initial boot still failed at 50% after turning it off.

    But again, I rebooted the system by using the power off/on with no special keys and it is running.

    the only thing that still puzzles me is the progress bar that appears during initial boot and is there for about 50 seconds.

    but everything works fine.

  • by may231998,

    may231998 may231998 Oct 27, 2014 1:39 PM in response to L1C
    Level 1 (0 points)
    Oct 27, 2014 1:39 PM in response to L1C

    Any success here?  I have a bunch of macs at our business that are doing this.  I can reboot to safe mode and get them to come up - but that's kind of a band-aid.

  • by Old Toad,

    Old Toad Old Toad Oct 27, 2014 2:04 PM in response to may231998
    Level 10 (141,085 points)
    Mac OS X
    Oct 27, 2014 2:04 PM in response to may231998

    Have you tried reinstalling the system from the Recovery volume and then repairing disk permissions?

  • by bdubes,

    bdubes bdubes Oct 30, 2014 10:35 AM in response to DlacVal
    Level 1 (0 points)
    Oct 30, 2014 10:35 AM in response to DlacVal

    had the same issue.  here is what worked perfectly

     

    1.     Reset the SMC -

    2.     Reset PRAM

     

    MacBook Air SMC and PRAM reset

     

    took 30 secs and rebooted and VIOLA, instant fix.

     

    I had FileVault turned ON in Mavericks before the upgrade install and didn't need to do anything with that.  FileVault works fine.

  • by kdh05,

    kdh05 kdh05 Oct 30, 2014 9:05 PM in response to may231998
    Level 1 (0 points)
    Oct 30, 2014 9:05 PM in response to may231998

    Check out the ~11th reply in this discussion.  It seems to be related Active Directory.

     

    By the way, for all the comments above about safe boot... That isn't needed (red herring)...  Just reset the PRAM and boot with the network unplugged, with wireless turned off.  See the discussion I linked at the beginning of my reply.

     

    I hope that helps.

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