After upgrading from Mojave developer beta 2 to developer beta 6, a ton of things broke and stopped working. Even on developer beta 8 (build 18A371a) this issue persists.

One of these things is the function keys, but only after a while. I tend to leave my MacBook Pro on overnight, and after that, the function keys stop working.

I've tried killing SystemUIServer and letting it restart, but that doesn't seem to work. The only solution I've found is to reboot the computer.

I'd like to be able to turn my keyboard backlight back on after closing the lid. I'd like to be able to adjust the volume without going to System Preferences.

The only keys that don't do anything are brightness, keyboard backlight, volume, etc, the ones that show a slider on the screen. The mission control key still works (enough, even though DB6 broke it horribly), the Launchpad key still works, media keys still work...

Is there a way to fix my function keys without a reboot? Rebooting can be extremely cumbersome at times and a huge inconvenience.

I have a normal, physical keyboard (thank god I don't have a touch bar), with physical function keys. Most of the controls work, and the ONLY controls that DON'T work are the ones that trigger sliders like the following to show on screen, which are the brightness, illumination (keyboard backlight), and volume controls:

My build number is 18A371a. When these keys stop working, some other things stop working as well, such as About This Mac, the sleep/restart/shutdown controls, the Messages app, as well as some other things. It really seems like some critical process is crashing, but I don't know what to restart.

Update: I found which process is crashing, and I have submitted a bug report to Apple:

The Radar number is 4873261.

  • Comments are not for extended discussion; this conversation has been moved to chat. – bmike Aug 25 '18 at 22:42

It seems like loginwindow likes to crash sometimes on Mojave, so this may be your issue.

To fix it, you'll need to kill loginwindow using Activity Monitor. It will log you out, but should hopefully fix the issue. You can also use this terminal command:

sudo killall -9 loginwindow

loginwindow listed as "not responding" in Activity Monitor

Also, if you are running any code injector, make that the first thing you shut off. It seems obvious, but it's happened.

  • Okay, so I guess a logout is necessary. It's not my favorite solution, but it's the only one I guess. – Dev Aug 26 '18 at 21:25
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    This does send an abrupt kill signal to all apps - preventing any that might clean up work or save state from doing so. But - heck, you're on a beta so why not just kill all the user processes if it gets you back to work faster than choosing "log out" – bmike Aug 26 '18 at 21:27
  • Fair enough. In all fairness, I told him "wait for the stable release" at least 200 times. – Charlie Welsh Aug 26 '18 at 21:29
  • @bmike "This does send an abrupt kill signal to all apps" - yep. Charlie, you expect me to wait for dark theme? Nope :P – Dev Aug 26 '18 at 21:40
  • I created a script that tells me how close loginwindow is to crashing: gist.github.com/LoganDark/b8c74e14c06b77e6f16d4492c5bda928 – Dev Aug 27 '18 at 9:31

I would try just logging out to see if that restores the process that handles function keys. Be sure to run sysdiagnose right after you restart and then once when you find the keys not responding, since Apple would surely then be able to fix whatever process is crashing if you can document it during the beta process with evidence captured in the system diagnosis.

The log out process can signal to apps to clean up and is much faster than a restart of the whole OS (which also calls the log out process first).

If you're looking to track this down, try to determine if the failing process is user level or system level. Knowing that will help you with the quickest fix and help apple fix this in code for a next build.

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    Unfortunately, I'm not willing to restart every process running under my user account every day. – Dev Aug 26 '18 at 17:26
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    @Dev You would only do this to isolate where the issue is if you care to know what's really happening. Isolating the issue also ensures it's most likely to be fixed - but you're in your right to just complain and say what you do and don't want to do. Posts that are "ton of things broke" but that when you restart they work indicate this isn't just an obvious flaw. What if it's your situation where your apps can't take a restart is causing the corruption? Log out and log in takes me 3 minutes tops. – bmike Aug 26 '18 at 18:44
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    "Log out and log in takes me 3 minutes tops" Well, please consider the fact that while I have unsaved documents open, persistent network connections open, and a ton of startup items that I can't find out how to disable, it turns into a pain in the ass to log out and log back in every day when the function keys and half of macOS just suddenly stop working. – Dev Aug 26 '18 at 21:19
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    I get it @Dev that you're irritated and fully expect your workspace doesn't save state, and is a royal pain to get set up - I don't suggest you change your ways lightly or feel it's going to be easy - just that the path to happiness on OS X is to be organized and run a stable release if you crave that above all else. I kind of love that you chose the logout method and accepted that answer by your friend. It's a super clear answer and points to the culprit. Thanks and good luck with the beta! – bmike Aug 26 '18 at 21:23
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    "chose the logout method" It's the only method that works, what did you expect? I would've chosen anything else that didn't involve logging out, but this is the only solution because loginwindow is indeed freezing. I know why, I'll submit a bug report. – Dev Aug 26 '18 at 21:27

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