A fix for the OS X Black Screen of Doom

How I lost a whole week to an OS X bug and how you might avoid the same fate

I have just been through a week of hell with OS X and I think I’ve found an answer to a problem that many OS X users have experienced: OS X 10.11.1 (“El Capitan”) boots to a black screen with the mouse pointer located in the upper left hand corner and that’s it. I found I was able to boot into “safe” mode but, on a 5K iMac, that’s like trying to run a Ferrari on lighter fluid.

This all started when we left to visit relatives over Thanksgiving week. On the day before leaving I got paranoid and decided to disable automatic login on on my iMac so that if my house was broken into and my machine was stolen, the bad guys would be slowed down and, because it seemed like a good idea at the time, I selected “Use iCloud password.”

So, I shut my iMac down, had a great holiday, got back to my desk on the  Monday following Turkeymas, and fired up my iMac only to be greeted with the Black Screen of Doom.

I’m going to spare you a blow-by-blow account but let me share the highlights which, for many, will still fall into the tl;dr category:

I rebooted into safe mode, noodled around, couldn’t figure out what was the matter and rebooted. The problem went away! I assumed to was a glitch and that the problem was solved. I was so very wrong …

I had to update some software that required a reboot and the Black Screen reappeared. Reboot to safe mode, OS X okay, reboot to normal, Black Screen. Rinse, repeat. No change.

I immediately started what turned into hours of online research and testing but all that revealed was this kind of thing has happened to lots of OS X users both before and since 10.11.1 and most of the solutions were along the lines of “try this” rather than a definitive “here’s the problem, here’s the solution, do this.” I tried everything and anything (I almost resorted to a prayer to St. Jude) but no luck.

Finally, on Thursday, I called Apple Support and, I have to say, the company has a smooth tech support operation. Friendly, efficient staff, with an impressively fast response but, alas, things didn’t work out so well. They suggested all of the same fixes and tests that I’d already tried and finally we wound up wiping the drive and began to restore a previous version of the system from Time Machine. 

Somewhere in the mix and after the wipe I wound up speaking to a level 2 tech who told me that all I needed to do was delete /Library/Preferences/com.apple.loginwindow.plist as it was probably corrupted. He told me that the level 1 didn’t know about this. In my head I cursed the entire organization.

At this point I was also cursing the gods of computing as a restore from Time Machine over the network from my NAS was estimated to take in excess of 26 hours. At least I could restore to the last backup which would make things easier and so, just over a day later, my machine was back to where it had been and, on Saturday morning, I fired it up in safe mode thinking all would be well once I wielded the delete key. Of course, it wasn’t. After I deleted the file my iMac still booted to the Black Screen of Doom. 

I called Apple Support again and got passed to a level 2 tech who was great. Patient, light-hearted, big props to James T., a senior Mac advisor, who assured me that he would take ownership of the problem and hang on the phone for as long as necessary. James joined me over a remote terminal session (which was painfully slow and made my iMac run even slower) so we could run Apple’s diagnostics after which James dispatched the results to engineering. James promised to call back on Sunday at 3PM with an update.

I was now a week behind in my various projects and so I started trying to catch up and, well, you know how it is when you stop thinking about a problem and your mind starts working in the background? That’s what happened and a couple of hours later it hit me: I’d switched on iCloud authentication! What if that was the problem?

I’m only theorizing here but I suspect that the Black Screen was actually a login screen for iCloud which OS X wasn’t showing probably because some other configuration file was corrupted as com.apple.loginwindow.plist had been thought to be. I switched off iCloud authentication and reverted to local authentication and, just like that, the problem went away. No more Black Screen of Doom ...

So, if you run into the OS X Black Screen of Doom, there’s your answer; don’t use iCloud authentication.

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