Black screen on login window on Mac OS High Sierra

try this..

1. Disable guest user in system preferences and reboot.

2.Run this in terminal to list all active/hidden users

------> 

3.if u still find "Guest" in the list:

run this in terminal:

------> sudo dscl . delete /Users/Guest

4. reboot.

Hello A-threddy,

The attached picture shows what my login screen now look likes. I have verified that the Guest User account is OFF in system preferences/Users & Groups.

When I ran your command listed in step 2 of your post, I was returned with what is also pictured in my attachment.

My question is, what belongs "normally" when I run your step 2 command?

Thanks,

I have the same problem. Mid 2011 mac mini, Sony TV display. Worked fine with Sierra, upgraded, now I have the black screen issue. Replugging my hdmi cable clears the problem, so it's an annoyance. I tried the defaults write … command, rebooted, the problem is still present.

Try this,

1. Restart (or start up) your Mac while holding down the Command and R keys.
2. When the Apple logo appears, let go of those keys.
3. The Mac will start Recovery System.
4. A window called Mac OS X Utilities will appear.
5. Click Utilities -> Terminal
6. Type in <cd /Volumes/Macintosh HD/Library/Preferences> - without <>
7. Type in <rm com.apple.PowerManagement.*>
8. .Type in <reboot>

And you are good to go...

Try this,

1. Restart (or start up) your Mac while holding down the Command and R keys.
2. When the Apple logo appears, let go of those keys.
3. The Mac will start Recovery System.
4. A window called Mac OS X Utilities will appear.
5. Click Utilities -> Terminal
6. Type in <cd /Volumes/Macintosh HD/Library/Preferences> - without <>
7. Type in <rm com.apple.PowerManagement.*>
8. .Type in <reboot>

And you are good to go...

I'm using Mac book pro early 2015 model, and i have the same problem as you mentioned there that an unknown guest user id shows up when login on my mac. could you please guide me to get rid of it? if i want to uninstall the Os high Sierra and reinstall it, how do i do it? if i do the reinstall and stuff will my data such as Microsoft office pack be wiped out? because, even if its wiped off will i be able to reinstall as it's before? (it's a home student package).

Thank you.

This doesn't apply to my system. There is no Guest user account. Verified with 'dscl . -list /Users|\

grep -i guest'.

BTW it's not just at boot time. I also see a black screen on wake from sleep.

I did observe that the black screen problem is fixed if I switch the input on the TV, then switch back to the HDMI input the mini is connected to. Then there is a normal login window and everything works.

I have two Guest users on login window!! when guest user is activated (see below). One with a strange avatar and an unknown password!!

I was able to resolve this issue by running the following command in Terminal:

sudo fdesetup remove -user Guest

(Credit Smoovejayy)

Ran diagnostics as suggested. No trouble found. Booted to recovery console, ran disk first aid. No problems found.

Reset SMC. Black screen at boot time still a problem.

try this..

sudo defaults write /Library/Preferences/com.apple.loginwindow SHOWOTHERUSERS_MANAGED -bool FALSE

then reboot.

You mean, first i have to restart and while the black screen appears have to press command + S key then i have to give the commands as you mentioned above right?

tried this on terminal, a command 'password' comes up after i entered the coding u mentioned, it doesn't allow me to do anything after that.

thank you! it worked. the unknown user has been deleted.