I'm running a Mac mini (late 2012) with OS X 10.8.2 as a media center PC and streaming server. It's not running 24/7 - instead I'm using a schedule to wake it up in the evening and putting it back to sleep at midnight. So far, so good.

For some reason the built-in VNC server stops working when the Mac wakes up while the attached screen is turned off. I can login and can also move the cursor but the screen remains black.

A workaround is to use RealVNC but I prefer to use the built-in VNC service since it doesn't cost extra money and has better multi-user support.

1 Answer 1


This was eligible for me: edit /Library/Preferences/SystemConfiguration/com.apple.Boot.plist like this:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
    <key>Kernel Flags</key>

and restart your mac. Mountain Lion forces me to enter password twice but it wakes up and works.

  • Many thanks! This worked for me. Instead of the black screen I see the remote machine's lock screen now. So the first password prompt is shown by the local VNC client and the second one is the login screen on the remote machine – is this what you meant?
    – aaronk6
    Commented Feb 21, 2013 at 18:31
  • Oh no, it just happened again :(
    – aaronk6
    Commented Feb 21, 2013 at 20:56
  • It seems that's an issue =( Found this: mactips.dwhoard.com/mactips/system/wake-on-demand Commented Feb 25, 2013 at 9:14
  • I think the issue I'm having is a different one. I can wake my machine using SSH and control it using the command line. So it is awake and only the screen remains black. I guess I'll wait for 10.9 and if it doesn't work either, I'll sell the Mac mini and test something else.
    – aaronk6
    Commented Feb 25, 2013 at 17:49

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