Black screen after Sierra update (today)

You wrote that the problem reappeared after using "Onyx":

After several days working well, today after using Onyx the black screen returned.

I'd like to understand it also, but I don't use clever tools like "Onyx", and have not experienced that problem.

The first thing to do with a misbehaving Mac is to get rid of totally useless garbage such as "Onyx" and "AVG". Such things cannot possibly convey any benefit and their presence will only complicate troubleshooting.

"AVG" may prove difficult to eradicate. Like many other ill-conceived junk products, its uninstallation instructions do not work, a typical characteristic of garbage software that should never be installed on a Mac.

If you want your Mac to work, stop preventing it from working.

When I determined its uninstallation instructions did not work, I erased the Mac completely and restored its content from a Time Machine backup.

Follow its uninstallation instructions for now. It has been a few months since I performed that evaluation, and they may have been updated.

for me it worked just to enter my account password and hit enter. the desktop appeared immediately.

i've tried hard rebooting, resetting NVRAM etc. without any effect.

(rMBP, late 2013)

John Galt wrote:

The first thing to do with a misbehaving Mac is to get rid of totally useless garbage such as "Onyx" and "AVG". Such things cannot possibly convey any benefit and their presence will only complicate troubleshooting.

John, I strongly agree with you about not using any kind of antivirus or other crap on our macs.

However, I strongly object to your lumping together OnyX with that lot.

This is a utility that has been around, free of charge, for over a decade.

What it does is to provide a graphical user interface to some system settings and to run some commands that would otherwise require a trip to the terminal - like selecting which format to use and where to store your screenshots, for example.

Not to use lightly, but certainly a respectable program.

Exactly the same happened to me. After much fruitless searching, I came across the fix - when you see the black screen, type the first letter of your user name (even though you can't see it) and hit return, then type your password and hit return.

This cured the problem instantly for me - apparently it's something to do with the update install not quite completing as it should.

...and then I read all the other replies! Sorry for the duplication

My version of this problem is that the black screen and cursor show up just after I login -- curiously, using the "guest user" login doesn't occasion this problem. I've now twice used this recent fix from single-user mode: http://betanews.com/2016/12/15/blank-screen-cursor-macos-update-fix/

-- I suppose if I keep my rPMB (late-2013) from going to sleep the problem can be avoided for the duration. Having upgraded from Mavericks a couple days back, I can't TimeMachine back to an earlier version of Sierra (10.12.2 worked fine at first).

Thanks for all the advice and comments on this thread!

Do you have to write your password on that black screen each time you restart?

ShemThePenman wrote:

My version of this problem is that the black screen and cursor show up just after I login -- curiously, using the "guest user" login doesn't occasion this problem.

This suggests it is something in your account (login items, launch agents, applications) which may be causing the problem... Does it occur if you start in Safe Mode?

If it doesn't, as I suspect it won't, it will confirm it is something like the above.

You may want to run Etrecheck and post its report.