Q: El Capitan update won't boot

Yep, this helped me.

Once I'd rebooted in recovery mode then installed a clean version of El Capitan and waited the hour or so for it to install, I could access and open Terminal then copied and pasted in the sumo command "sudo rm -rf /System/Library/Extensions/EltimaAsync.kext " and pressed return.  Needed to enter my desktop password for it to complete and ignored a warning, but once done I quit Terminal, shut down, and rebooted the iMac fine.

Then also had a problem with Calendar hanging as it was stuck 'moving Calendars to the server account' and found that logging out of iCloud and logging back in again fixed that one.

Now all's fine.  Thanks.

I should be so lucky. Cannot boot up in Safe Mode. In recovery mode, can only re-install El Capitan. It won't let me go back to Yosemite. Bone-stock Mac Mini less than one year old.

Tim,

If you need data that is on your computer, and don't have it backed up, try this:

1. Re-install El Capitan from recovery mode.  This might let you log in once, but not for re-starts.

or

2. Access your hard drive from target disk mode (hold T through the start up until you get the thunderbolt screen).  This will require another mac and a thunderbolt cable.  Have the thunderbolt cable plugged in and good mac turned on before you turn on the bad machine.

Once you have your data, you will be looking to wipe your drive and re-install Yosemite.  Try this:

1. Start up in recovery mode, use the disk utility to erase your disk (the one labeled Macintosh HD).  Select OS X journaled format, and name the disk.

2. Shut down.

3. Start up in internet recovery mode (command + option + R) on start.  This should allow you to re-install whatever version of OS X came installed on your computer (I'm guessing Yosemite). 

4. If it is Mavericks, you can then upgrade to Yosemite through the App Store on your Purchased page.

5. You should then have access to all your App Store Apps on the Purchased page.  If some of them won't install, call Apple and they will give you a code to redeem for a new version.

6. You will have to go re-download your third party apps (make sure you have product keys, etc.)

After about a week of trouble-shooting, I finally had to do exactly as I outlined above.  My computer is running great now though.

Best of Luck!  Hope this helps.

Jon

Yippee; it seems that despite thinking that I did not have "EltimaAsync.kext" in my Extensions Library, in fact I did. Once I had deleted it my MacBook Air restarted OK. Keeping my fingers crossed that this is always the case.

Seems Apple missed a trick here as this seems to be a leftover extension that did not uninstall correctly. From these posts, seems like a few people had this extension. Come on Apple look lively!!!

Hi dreamzonebe, where you able to find a solution? 

I have the exact same problem... apple logo no progress in load bar... already installed the OS twice... after install it works, but after rebooting it won't  load.

Hi, removing this extension (EltimaAsync.kext) cleared my problem; El Capitan now reboots and restarts from power off without any problems. It is easy to removeGo to your Macintosh HD drive and find extensions and look for this extension and delete it then reboot.

on recovery mode ( command R )... terminal opens bash and sudo throws command not found! ***?

plus cant find EltimaAsync.kext extensions doesn't seem to exist

I'm reinstalling for the 3rd time for now

thanks bluegolf, Tried that, but from recovery mode I can't find that extension and sudo throws command not found. What am I missing here ?

On my Mac mini, the problem was solved after a new install over the previous el capitan. Without formatting or anything else.

On my iMac I had to do a full clean install. I left the computer on before leaving the office when it seemed to have frozen with 1 second remaining on the 4th attempt to install. In the morning the installation was complete and the computer works fine since. It seems I was very lucky as the problems keep on continuing.

Don't go into recovery mode. Reinstall OS X and once it is running, go to Finder and ensure that in preferences the Hard disks are highlighted. Then look in the systems/library/extensions file for Eltimaasnce.kext. I tried the recovery mode and I could not find it either but as soon as I did what I have suggested and deleted everything was hunky dory.

Can only say that it worked for me but from many on the posts on here Eltimaasync,kext is the problem. I found this by booting in Verbose mode which shows you where the boot cycle fails. From this I could clearly see that Eltimaasyne was the issue. Good luck

bluegolf, you're star - finally located the bugger! But will hold off restarting for now, just in case...., until it's absolutely necessary but thanks for that! Will let you know how things go.

I am glad this helped you but I removed EltimaAsync.kext last week and it did not help. There must be more bugs for this to be affecting so many different macs running different earlier os's.

Ross

Hi Ross, 

I agree there are other third party extensions which are preventing El Capitan from loading. You need to look through the extensions library and identify those that are not required. I also agree that it is a tedious process!!

I decided to stop screwing with this until apple releases their first update. I have already blown plenty of my time with this. The other thing is that I have a 1tb ssd in my Mac. From everything I have read over the years, these drives have a limited r/w life span and I am not happy with reloading hundreds of gb's over and over each time I need to reload from my time machine backup. 2 try's so far is enough for now!

Ross

TErminal and removing eltima kext helps me, thanks a lot for  everybody!