After startup my iMac's screen turns black

Any ideas on how to handle this,? I get to start up screen, then 1 of two things happens. The picture attaches or it all goes blank. This happened after I tried to install sierra. I think I got my MBP in 2012

The screen implies a type of 'kernel panic' or error has occurred.

You may be able to get into the system at some point and see

what the exact panic log suggests; or use some information to

see if you could de-bug or understand what it means. Messages

of this type tend to be cryptic.

{If you have a time machine and time capsule backup, you may

be able to restore your computer from the copy backup prior

to this latest problem. There also may be some kind of hardware

issue whereby the hard drive could have a defect. They do fail.}

Note the 'Understanding and Debugging Kernel Panic' site

link below for more details about this aspect of the topic.

And although I cannot view details from the small image, it would

appear that an 'admin' account has some kind of problem. Image

posted details really are too small text to read with certainty.

• Resolving Kernel Panics - thexlab faqs:

http://www.thexlab.com/faqs/kernelpanics.html#Anchor-Troubleshooting-49575

You may see if a Safe boot could work to get past the panic screen.

• Use safe mode to isolate issues with your Mac - Apple Support

• OS X: About kernel panics - Apple Support

• Mac OS X: How to log a kernel panic - Apple Support

• Technical Note TN2063: Understanding and Debugging Kernel Panics:

https://developer.apple.com/library/content/technotes/tn2063/_index.html

You may be able to startup in Recovery mode, to see if the version in the

computer (hard drive, partition) of recovery still exists; if so then you may

be able to re-install that version. If not, then you'd have to consider what

was damaged; this may then require you to use online Recovery mode to

see about using Disk Utility to repair the hard drive, or a reformat/reinstall.

• About macOS Recovery - Apple Support

There are different keyboard choices to enable the various startup and

uses of Recovery; and a resulting different macOS may be available if

you use the online recovery compared to the one inside your Mac HDD.

Good luck in this matter...! 🙂

All: I tried all of the solutions in this thread and many others. I finally decided to call Apple Care...(even though my iMac is out of warranty). I was on the phone for maybe 10 minutes and my problem was resolved.

Apple is investigating the issue and its causes and said that they will assist ANYONE who calls in with this issue (whether your Mac is in warranty or not).

They had me go into single user mode and after a couple short commands I was back in business. (Sorry, I do not remember the commands)

The gentlemen I spoke to was a senior advisor (Shane Boyle) and he even asked that I reply to a couple of the threads informing people that they can call for assistance even if your mac is out of warranty. He was very pleasant to talk to and very knowledgable. Thanks Shane!

Thank you VERY much. This happened to me last weekend after a Sierra update. I ended up nuking and paving to get the iMac back! Then, this morning, after another stupid OS update, it did it again. I done another nuke and pave but this time no luck until I found your post.

First letter of my login TAB my password. BANG!!!! back to normal.

Just tried a restart and..... thank you, thank you, thank you! Normal service has been resumed!

Paul

Cannot say as I've done so, in part because Westchester (?) isn't within

few thousand+ miles of here. ~ However I've sent a portable Mac to repair

at distance of 3,000 air miles one-way. That was still cheaper than nearest

local estimate of authorized service provider (hardware repair) 200 mi away.

What was the rest of your question?

Looks like that part was cut off... 😉

Will it start more normally if you choose to hold the Shift key down through startup and then you may be able to see the desktop and login...? This would be SafeBoot mode.

If so, then it could be troubleshooted or console utility logs looked into, to see if there is any evidence of system parts not loading properly, or of a hardware issue. Or a graphics problem after the system loads.

SafeBoot starts the computer in a reduced OS X so several items are turned off.

With an AppleCare plan in effect, you should consider making an appointment

with a Genius at the Apple Store, to take the computer in for diagnosis.

Especially if this repeats itself; that would make it easier to prove a point.

Have you used this computer with an external display?

In safeboot mode, if it starts you could check some other things in the system.

However there are keyboard shortcuts on startup that

may be able to troubleshoot past the problem.

•Intel-based Macs: Resetting the System Management Controller (SMC)

http://support.apple.com/kb/HT3964

•About reset the NVRAM (so you tried it, more than twice?)

http://support.apple.com/kb/HT1379

PS: there may be two things to try:

two workarounds:

Put the computer to sleep (close the lid on a Mac Book (pro) or press the power button quickly on a desktop Mac. After a few seconds of sleeping, wake the computer up again. The login dialog usually appears now.

2. Sometimes you do not want to put the computer to sleep because you do not want to interrupt a task that is running. In this case, press CTRL+SHIFT+EJECT. This keyboard shortcut usually locks the screen. In out case, locking the screen also enables or resets the screen saver, so that the next key press or mouse motion will bring up the login dialog.

Good luck & happy computing! 🙂

I found my computer in the same position today. Turning it off and restarting just get black screen with mouse curser. Will not go into safe mode only black screen. Can however do option button and control r to get screens but nothing will get me log on. Disk utility is not showing errors. When it does go from apple grey screen to black screen it does show a little something on the screen then goes to black page. I did get it on video but dont know how to put on here. Please help. Any suggestions. Installed maverick on or about February 19th. Would a board have gone out? Any idea which one. Not in warranty anymore.

If you haven't found a solution to your problem yet, then here you go.

1. Shut down your computer by holding your power button for 5 seconds

2. Start it up and hold the shift button through startup until you see a bar

3. When it gets to the black screen, type the first letter of your name and then hit TAB and type your password

4. The rolling mouse should appear and the screen will go black again

5. Hit the space bar and you should see an installation. Let it install and your good!

Hi aappleman

i have exactly the same problem. Tried everything, also your method but when hitting space bar, screen stays black with a faint light. i can see the cursor.

what to do???

THanks simon

Had the same issue and this helped! You're a life saver, thanks!!!

It took a few clicks but it works now! The only thing is that when the graphics are slow to download when I switch desktops.

Thanks aappleman!!! This was extremely helpful! I was in a panic that I would have to dish out big money to get this fixed! You're a life saver!!!

Thank you so much that worked for me too!!! I tried everything before this. My sound doesn't work now and some of my screens do a strobe light type of flash. It's better than a black screen though. Any advice on how to get sound back and fix the scene flashes?

Sam