I'm having a problem with my macbook where, for some reason, when it's unplugged to the power the computer randomly turns the screen semi-black (not totally black) and starts the fan at max power. The computer itself is still on (the apple is bright) and I have to turn it off by long pressing the power button.

I'm not able to understand what is going on:

The logs from system.log

Apr 19 09:15:03 marco com.apple.xpc.launchd[1] (com.apple.sandboxd[153]): Service exited due to SIGALRM | sent by kernel_task[0]
Apr 19 09:15:03 marco syslogd[96]: ASL Sender Statistics
Apr 19 09:15:05 marco com.apple.xpc.launchd[1] (com.apple.bsd.dirhelper[9925]): Endpoint has been activated through legacy launch(3) APIs. Please switch to XPC or bootstrap_check_in(): com.apple.bsd.dirhelper
Apr 19 09:15:05 marco systemstats[107]: assertion failed: 18D109: systemstats + 676139 [952918BC-3D73-37CE-8C6A-851AAF3C70D1]: 0x7f946c61bfe0
Apr 19 10:13:48 marco syslogd[96]: ASL Sender Statistics
Apr 19 10:13:48 marco com.apple.xpc.launchd[1] (com.apple.newsyslog): Service only ran for 8 seconds. Pushing respawn out by 2 seconds.
Apr 19 10:13:49 marco fud[9987]: objc[9987]: Class MobileAssetUpdater is implemented in both /System/Library/PrivateFrameworks/MobileAccessoryUpdater.framework/Support/fud (0x1029ab908) and /System/Library/AccessoryUpdaterBundles/ApplePowerAccessoryUpdater.bundle/Contents/MacOS/ApplePowerAccessoryUpdater (0x1054b2a68). One of the two will be used. Which one is undefined.
Apr 19 10:14:01 marco timed[133]: settimeofday({0x5cb98349,0xeea4a}) == 0
Apr 19 10:14:03 marco com.apple.xpc.launchd[1] (com.apple.duetknowledged[10064]): Could not find and/or execute program specified by service: 2: No such file or directory: /usr/local/libexec/duetknowledged
Apr 19 10:14:03 marco com.apple.xpc.launchd[1] (com.apple.duetknowledged[10064]): Service setup event to handle failure and will not launch until it fires.
Apr 19 10:14:03 marco com.apple.xpc.launchd[1] (com.apple.duetknowledged[10064]): Service exited with abnormal code: 78
Apr 19 10:20:55 localhost bootlog[0]: BOOT_TIME 1555662055 0

Where 10:15 is the computer still on, but close to the time of "death". I left it running from 10:15 to 10:20 (in this time the fan was running at fullpower) where I turned it off, but nothing appeared in the logs for that time period (weirdly)

Do you have any suggestion on how to debug and fix this issue? I might consider formatting everything as a last resort but I prefer not to because I have a lot of setup of various work projects

OSX Version: 10.14.3

  • Can you run diagnostics and report back if something pops up? Does the same happen when you boot into the recovery system pressing cmd+R while booting? – n1000 May 2 '19 at 7:15
  • Did you try SMC and NVRAM reset? Among other things, SMC manages "Thermal management". – n1000 May 3 '19 at 9:44
  • @n1000 yes, it happens on recovery as well. Trying the diagnostics now – Marco Acierno May 4 '19 at 13:03
  • @n1000 diagnostics report everything is "fine" – Marco Acierno May 4 '19 at 13:12
  • I fixed the problem, posted as an answer. – Marco Acierno Jun 8 '19 at 16:31

If the screen is semi-black, it should change the brightness of the logo as well. Not sure how one is happening and the other is not.

Before you proceed, you might wanna take a backup of your data.

Do the below:

  1. Reset NVRAM or PRAM on your Mac - https://support.apple.com/en-us/HT204063 How to reset the System Management Controller (SMC) on your Mac - https://support.apple.com/en-us/HT201295

  2. Install Onyx and try to fix system issues - https://www.titanium-software.fr/en/onyx.html It's a powerful and reliable system maintenance app

  3. If you are an advanced used, try live usb booting with Linux and see if the same problem happens. If it doesn't, then the problem is with macOS. You might need to format your mac. If it does, then you might have a hardware problem and should be handled in a different way.

Glad to be of help. Let me know how this goes.

  • Tried a few things I will see what happens. If it still happens I will try the Linux solution. Thank you :) – Marco Acierno May 4 '19 at 13:39

I fixed the crash, the problem seems to be caused by a problem in the kext of the Thunderbolt port.

Steps to fix it:

  1. reboot with CMD+R pressed.
  2. open Terminal
  3. sudo csrutil disable
  4. reboot in normal mode
  5. sudo mv /System/Library/Extensions/AppleThunderboltNHI.kext /System/Library/Extensions/AppleThunderboltNHI.kext.BAK
  6. reboot with CMD+R pressed
  7. csrutil enable
  8. reboot and forget about problem

If you do not use ethernet via thunderbolt you do not need this kext, once removed the driver the crash won't happen anymore. Also, every time you update your mac you've to repeat all the steps here.

I found the solution here:



Did you install a Duet dongle on your laptop but not finish installing/uninstalling the software? Perhaps you installed it before you updated macOS?

Does https://www.duetdisplay.com look familiar at all?

Did someone plug an iPad with the Duet software enabled into your Mac?

Does this happen when you unplug EVERYTHING from your Mac -- don't leave any devices connected to the ports.

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