#define private public - Macbook hangs after installing OS X 10.11.1 (31 Oct 2015)

topic end
<!--
   * Set TOPICTITLE = #define private public - Macbook hangs after installing OS X 10.11.1 (31 Oct 2015)
-->

<style type="text/css">
pre {background-color:#ffeecc;}
</style>

%STARTINCLUDE%
<a name="31"></a>

---+++ [[DefinePrivatePublic20151031MacHangsAfterInstallingOSX10111][Macbook hangs after installing OS X 10.11.1]] (31 Oct 2015)

<summary>
In more than two years of owning a Macbook, I never faced a single issue upgrading the OS. Until today when, after installing the 
[[https://support.apple.com/kb/DL1845?locale=en_US][OS X 10.11.1]], the Macbook would just hang after rebooting.
</summary>

More precisely, the progress bar on the boot screen would stop at roughly two thirds of the way. So today, finally, I had to figure
out what kind of diagnosis and recovery options OS X actually provides.

The two most important tools were:
   * &#8984;+V during reboot: Boot in verbose mode, showing the boot messages instead of the Apple logo and progress bar. I noticed 
     that the boot process hung after a message saying <tt>pci pause: SDXC</tt>.
   * &#8984;+R during reboot: Boots into [[https://support.apple.com/en-us/HT201314][recovery mode]], 
     which offers tools for disk and networking diagnosis, as well as
     the option to open a terminal as a superuser.
 
Things I tried:
   * [[https://support.apple.com/en-us/HT201295][Reset the System Management Controller (SMC)]]
   * [[https://support.apple.com/en-us/HT204063][Reset the NVRAM]] - this actually changed the behavior; the progress bar would
     now fill up to 100%, but then nothing happened anymore. When booting in verbose mode (showing all the boot messages),
     startup continued past the <tt>pci pause</tt> message, but stalled later in what looked like a loop involving
     messages liked =IO80211AWDLPeerManager::setAwdlOperatingMode Setting the AWDL operation mode from SUSPENDED to AUTO=
     and =IO80211AWDLPeerManager::setAwdlAutoMode Resuming AWDL=. (See also http://superuser.com/questions/917220/macbook-can-not-boot-os-x-yosemite-as-it-hangs
     for a description of similar symptoms.)
   * [[http://osxdaily.com/2012/02/08/repair-boot-disk-mac-os-x-disk-utilit/][Repair my SSD in recovery mode]] - this found a
     number of issues on the disk and repaired them, but did not fix the hang-up issue.
   * Fix permissions using the [[http://www.apfeltalk.de/community/threads/installation-von-el-capitan-haengt-sich-auf.488782/][recovery mode resetpassword utility]]
   * [[https://support.apple.com/en-us/HT201262][Boot info safe mode]] - this did not work at all, as the hang-up apparently 
     affected safe mode as well.

I was dangerously close to reinstalling the OS now, with only two aces left up my sleeves: [[https://support.apple.com/en-us/HT201573][Single-user mode]] 
and kernel extensions.

I had seen references to startup issues related to kernel extensions in some articles, but knew very little about them. 
The first thing I tried was to temporarily disable kernel extension signing (<tt>nvram boot-args=kext-dev-mode=1</tt>), with no
discernible effect. Fortunately, at this point I came across
Justin Silver's blog article [[http://justinsilver.com/technology/os-x-el-capitan-10-11-1-hanging-on-boot-fixed/]["OS X El Capitan 10.11.1 Hanging on Boot"]]
in which he describes a startup issue which looks a _lot_ like mine. His excellent summary contains 
instructions on disabling kernel extensions using recovery mode - which helped me solve my problem!

I booted into recovery mode, opened a terminal window, and then:

<pre>
  $ mount -rw /
  $ cd /Volumes/Macintosh\ HD
  $ cd Library/Extensions
  $ ls
ACS6x.kext                   HighPointIOP.kext
ATTOCelerityFC8.kext         HighPointRR.kext
ATTOExpressSASHBA2.kext      PromiseSTEX.kext
ATTOExpressSASRAID2.kext     SoftRAID.kext
AX88179_178A.kext            hp_io_enabler_compound.kext
ArcMSR.kext                  hp_io_printerclassdriver_enabler.kext
CalDigitHDProDrv.kext
</pre>

Following Justin's advice, I moved all kernel extensions out of =/Library/Extensions= to disable them temporarily, and 
then rebooted. Lo and behold, the login screen appeared! After a few such rounds of moving kernel extensions back to
=/Library/Extensions= and rebooting, the root cause of my startup issues turned out to be those HP printer extensions.

Phew.

The HP kernel extensions had been on my system for quite some time, of course, and had never caused any problems like this before.
So there are still open questions about what exactly had happened here. To be solved on a rainy day.

Other related links:
   * http://apple.stackexchange.com/questions/163059/how-can-i-disable-kext-signing-in-mac-os-x-10-10-yosemite
   * http://superuser.com/questions/917220/macbook-can-not-boot-os-x-yosemite-as-it-hangs
   * https://jamfnation.jamfsoftware.com/discussion.html?id=12589
   * [[https://discussions.apple.com/thread/7252280?start=0&tstart=0][El Capitan update won't boot]] (Apple Support Communities)

---

Update January 2nd, 2016: Today it happened again - the !MacBook hung at the same point during reboot. I remember
I installed an HP scanner driver roughly a week ago, and I probably did not reboot since then. The above recipe
worked for me this time again.

---

Update November 2016: Apparently, the printer driver reinstalls itself automatically:

    <img src="%ATTACHURLPATH%/hp_printer_software_update_ScreenShot2016-10-27at13.57.07.png" alt="hp_printer_software_update_ScreenShot2016-10-27at13.57.07.png"  width="800" height="127"  />

See also https://support.apple.com/en-us/HT201465. Which explains the many times I have had to re-apply the workaround described above.
I guess it is about time to look for and eliminate the root cause of all this.

---

%STOPINCLUDE%

%COMMENT{type="below" nonotify="on"}%

---
to top
End of topic
Skip to action links | Back to top
You are here: Blog > DefinePrivatePublic20151031MacHangsAfterInstallingOSX10111

r1.7 - 27 Oct 2016 - 12:04 - ClausBrod to top
Blog