Q: Reboot fail after installing El Capitan help!!

Considering the age of your Mac (2011) this could be a hardware issue. If it is a hardware issue, it's usually cheaper to buy a new Mac than repair.

Do you have access to another Mac? If yes, you can use screen sharing to see if the problem Mac looks the same when viewed using screen sharing. This would rule out the monitor but there are other parts like a graphics card that could be going bad. If you could take your Mac into an Apple Store they could run hardware tests.

eg. I have a 2006 iMac. The monitor is shot. It's so bad you can't see anything. However, when I screen share, I can use the old iMac without any issues.

I'm in denial for the present anyway that this is a hardware problem. This computer worked perfectly for a couple of months and only began the freezing, crashing, not booting after I upgraded to El Capitan. This could be coincidence, but in reading thru this thread and others, 90% of the symptoms I'm having are mentioned by others and have been solved with software changes.

Unfortunately, I don't have easy access to another Mac.  My workplace has always used windows computers, so I have done the same. I have an external monitor; do you think connecting connecting to it would test the graphics card/monitor?  Is the graphics card on the logic board? A logic board for this model is $159, and the instructions for replacing it seem pretty straight forward - provided you have the tools.

Thanks!

Try booting into the Recovery Drive. If you see a strange screen in recovery, you'll know it's hardware.

Boot into the Recovery Drive by holding down Command R when restarting.

When you log in you'll see something similar to this. A gray background with a box OS X Utilities.

Lost my text when I inserted the images. Oh well, bottom line is that booting with command R bypasses the login and goes to the smooth blue screen - after 2-3 minutes. Also, doesn't restart itself as it does with a normal login boot attempt. I was successful with command R a couple of times early on. I reinstalled El Capitan and even bought a new hard drive and tried to do a clean install to the new disk. That didn't work, but it may not have been the computer's fault.

Hope you can see the difference in the images. The top one is what I get now when I startup - blue horizontal lines but still legible. The 2nd is the smooth screen that I think everyone calls the blue screen of death. I can go to terminal using command S and to disk option with the option key, but right back to the blue lines when I choose the hard drive.

I've been looking at the new Macbooks. They're really tempting put I'm not giving up on this one just yet.  With the I7 chip, this one still a better computer than what I can get for $500 in a windows machine.

Thanks again for your help.

When you booted into the recovery drive using Command R, did you ever see the box with OS X Utilities? If not, I suspect it's your install. I suggest you create a USB installer and try installing El Capitan from the USB drive. You'll need a working Mac to download El Capitan installer and prepare the USB drive.

http://blog.macsales.com/33160-how-to-create-a-bootable-el-capitan-usb-install-d rive-with-diskmaker-x

BTW, the MacBook was on sale for $300 off. Just ended.  http://9to5toys.com/2016/02/11/12-inch-retina-macbook-sale/

This site posts weekly updates to deals.

Story of my life, a day late and a megabyte short.  Thanks for the links; I'll find a Mac and try to create a USB installer.  To your question - when this problem first began, I was successful 2 maybe 3 times in booting into the recovery drive but not in the last couple of dozen attempts.  Just goes from blue lines to smooth blue.

Thanks again,

Since you were able to boot into recovery but cannot now, this seems to point to hardware. Let us know if you can boot up after running El Capitan from the USB Installer.

Will do.

Tks,

Hello GS from NL,

I've followed this thread for a while, but have perhaps a unique problem. Installed El Capitan on mid-2007 iMac. Stuck in reboot. Starts up with some progress before shutting down and rebooting continuously. Never completes the progress bar. No startup mode works for me. Safe Mode doesn't work. Neither does Recovery Mode. I am able to startup in Target mode and connect via Firewire from my MBP. Familiar enough with Terminal to cut and paste, but not sure how to find and delete kexts via Target Mode. Is there a simple command line prefix I can use to run your fix? Don't want to run Terminal on my MBP instead of the iMac.

Thanks in advance for your help.

Vance

Hi Tsofa:

I am having the same issue as many others. My imac keeps restarting after upgrading to el crapitan from snow leopard.

I tried using this terminal kexts command that you mentioned but it isn't working for me.

cd "/Volumes/Macintosh HD/Library/Extensions/" ; mkdir Unsupported ; mv hp* Unsupported ; mv B* Unsupported ; cd "/Volumes/Macintosh HD/System/Library/Extensions/" ; mkdir Unsupported ; mv Elt* Unsupported ; mv ssud* Unsupported ; rm -Rf /Volumes/Macintosh\ HD/Library/Application\ Support/Rox* ; rm -Rf /Volumes/Macintosh\ HD/Library/Application\ Support/Check* ;  rm -Rf /Volumes/Macintosh\ HD/Library/Filesystems/*fuse* ; rm -Rf /Volumes/Macintosh\ HD/var/folders/*

My HD is called MacOsx there is no HD in the name. Do I deleted everywhere it says Macintosh HD and replace it with MacOsx. Also I noticed that in other parts of the command it reads  Volumes/Macintosh\HD/Library/Application with this I am confused at what not to put.  Do I remove both Macintosh\HD or just Macintosh?

Thank you so much it helped me alot

macbook air 2011, stuck at boot screen after osx update...

This helped

https://www.justinsilver.com/technology/os-x-el-capitan-10-11-1-hanging-on-boot- fixed

1) boot to recovery mode (hold cmd-R at boot)

2) in terminal compare kexts in "/Library/Extensions/" and "/Volumes/Macintosh HD/Library/Extensions/"

   and remove some kexts from "/Volumes/Macintosh HD/Library/Extensions/"

  in my case HP and Canon printers

3) reboot and everything works again

still loading..... can't boot, now I'll try to clean install after cleaned up the partition

Thank you so much GSfromNL! After 2 days trying everything to reboot, your "step by step" help me and i got it working!

Hello GSfromNL,

Thanks for trying to assist everyone here on this thread with their Mac troubles.

When I put this command "system_profiler SPExtensionsDataType > ~/Desktop/kextList.txt", the terminal gives me this output. "/var/root/Desktop/kextList.txt: No such file or directory".  I actually recently installed an Antivirus, Avira. Had no issues with my mac, after doing the El Cap update for 2 months now. I need help!!!

PS Mac Book Pro think tis 2012/13 (not sure). 8GB RAM, 750 HDD