External monitor OS bug - Black Screen with cursor

There seems to be a nasty bug in the new El Capitan OSx with external monitors on my iMac 5k retina.


External monitor connected causes both monitors to show black screen with cursor at the point where the login would normally appear.


1. OS X Yosemite works fine and does not have this issue.

2. Upgrade to OS X El Capitan has this issue. Disconnect ext monitor boot again and its fine.

3. Clean install El Capitan on iMac from wiped partition and issue shows if ext monitor connected.

4. Restore Yosemite from time machine or install clean and issue does not happen.

5. Try several different monitors and same issue. Each connected by an original apple Thunderbolt to HDMI cable.

6. Each of these monitors work perfectly if booted under Yosemite on same machine.

7.If they are connected after login they then work fine, but if logged out, the issue shows again.

8. If monitor is disconnected before logout, then the issue does not show and the normal login shows.

No matter what i do, upgrade or clean install this is happening every time on El Capitan.

Hopefully someone at Apple will see this and acknowlege the issue or supply a workaround other than connecting and disconnecting the monitor.

NW

iMac with Retina 5K display, OS X El Capitan (10.11), Core i7, 32GB, 1TB SSD

Posted on Oct 4, 2015 4:42 PM

Reply
18 replies

Feb 21, 2017 7:43 AM in response to nicwilson58

This is also happening on my Macbook Pro Retina 15" Late 2013 running Sierra (10.12.3) using the HDMI output on a DELL S2409W Display. I'm connected to a charger, but no external peripherals (keyboard/mouse). This was working fine one day and all of sudden stopped working. Also having issues with Thunderbolt port as well, but I thought maybe it was the monitor since it was older and starting to give me other issues (slow to warm up/half purple for a little while, and screen jitter when it was working).


I sense a reboot may resolve it, but rebooting is frustrating. Guess I'll try that.

Oct 12, 2015 12:18 AM in response to nicwilson58

I have this same issue on my Mac Book Pro Retina 15" (Late 2012). No problems with Yosemite--problem started since El Capitan installed. I tried every trick in the book to get this to work (I use 2 external monitors.. Thunderbolt to HDMI and HDMI).. Tech support seems to have never heard of this and is dumbfounded. Any ideas are welcome.

Thanks!

Oct 28, 2015 12:46 PM in response to nicwilson58

I just experienced the exact same issue. I called Apple Support and the issue was fixed by plugging my computer to the charger. I was shocked to hear that as well. Apparently, in order for this feature to work you have to have the following 3 things:


1) An external mouse/keyboard connected to the Macbook

2) An adapter connected to the external monitor that is configured for "Mirror" arrangement

3) Macbook must be plugged in to the charger


I had the top 2 items and the symptoms were identical. As soon as I would try to use the external monitor alone, I would get a black screen with just a mouse pointer and nothing else. Once I plugged the laptop into the charger, everything worked fine. My Macbook is closed right now and I'm connected to my external monitor and everything seems to be working. I'm using El Capitan as well. Hope this helps.

Oct 28, 2015 3:48 PM in response to mayanTx

Hi guys,


I seem to have exactly the same issue. I am on Mac Pro (late 2013) and just recently updated to El Capitan. I can confirm that I have never had something like that happening on Yosemite, but here - I can no longer have a proper boot. Every time when I restart the computer - I get to this black screen. So all I can do is just trying to login blindly. The combination that works sometimes is hitting the first letter of my username, then hit enter and then put the password. At some point that works eventually and I am able to continue normally using the computer. It doesn't happen when I wake it from sleep, but only after restart. I have a secondary monitor connected via HDMI (well it's a Cintiq HD tablet actually, but still as far as OS is aware - its yet another monitor). I haven't trying reaching out to Apple support yet, but I also found other topics of other people complaining of similar issue.


I did apply the recent update, but that didn't work either...

Jan 23, 2016 2:06 AM in response to nicwilson58

Hi Nic - Paul from UK, exactly the problem you describe - very annoying!! I have the following:


iMac late 2015 5k

23" Apple Display (connector mini display to DVI) connected to one of the thunderbolt ports


On boot with external connected black screen pus cursor


If I boot with the external not connected and then connect the display all seems to be fine ... but this is a pain.


Paul

Apr 5, 2016 12:26 AM in response to circlegate

I have exactly the same issue. Brand new iMac 5K, connected to a 30" Apple Cinema Display with the Mini Display Port to Dual Link DVI (thunderbolt) adapter.


On start up iMac screen shows black screen with white Apple logo and quick loading bar then both screens stay black, however the mouse cursor is there and I can move it across both screens. Only solution was to unplug the Cinema Display and restart, then plug it back in after the iMac was running. What a pain...


I did find a work around! I got the idea from Sandspiel above (talking about trying to find the field for his login password), so I disabled the password on startup and tried restarting with the Cinema Display plugged in. It worked, as soon as the computer started up both screens came on simultaneously!


Turning off login password-

http://www.howtogeek.com/202411/how-to-login-to-os-x-yosemite-automatically-with out-a-password/


This is a workaround and not ideal for a laptop that could fall into the wrong hands. My iMac is a bit safer in my home, but it is still a huge problem and I am hoping someone figures it out...

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External monitor OS bug - Black Screen with cursor

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