Lately I've been having lots of issues with my Mac randomly freezing. As in, multiple times per week. These are the symptoms:

  • My screen freezes completely. The picture stays on screen and my computer doesn't respond to mouse or keyboard input.
  • If I have audio playing in the background, sometimes it will keep playing.
  • The Force Quit hotkey doesn't seem to do anything.
  • The only way out I've found so far is to force my computer off by holding Power.

How do I diagnose and fix the underlying issue?

Additional info

  • MacBook Air (13-inch, Early 2015)
  • 4 GB 1600 MHz DDR3
  • 27.34 GB free disk space (SSD)
  • Running apps when I notice this: Safari, Mail (there are others, but I'm not sure if they're running every time it happens so I didn't include them)
  • Activity Monitor screenshot: I can't, because I never know when the system is about to freeze up

As advised in the comments, I've disabled 'Allow WebGL' for now and I'll continue monitoring the situation.

  • Can you provide us with more specs? How much RAM, free hard drive space, HDD or SSD for the hard drive, which model of the Mac, a screenshot of Activity Monitor, what apps are running in the background when you notice this, if there's anything in particular that seems to trigger this.
    – kal-al
    May 27, 2016 at 19:51
  • Check logs for events prior to powering off. See Workaround for Freezing Macs with OS X 10.11.5 and OS X 10.11.4?. It would appear from the comments the underlying cause can be varied. Verify disks after powering off. A repaired file system can have content errors requiring OS X reinstallation to cure. Rebooting in safe mode can clear caches, solving some causes. There will be an OS X 10.11.6 release, with any luck addressing cures for the most common cause(s).
    – user90735
    May 27, 2016 at 20:46
  • @user1155120 Broken link.
    – Brick
    May 28, 2016 at 2:07
  • Workaround for Freezing Macs with OS X 10.11.5 and OS X 10.11.4? (Had an extra character on the end of the broken link).
    – user90735
    May 28, 2016 at 2:52
  • Updated my original post. I will run First Aid on the disk. I will reboot into safe mode later today.
    – Pieter
    May 28, 2016 at 7:40

1 Answer 1


If you still have another device around, you might try to SSH into your machine, as apparently only the GUI process is frozen. You'll be able to safely reboot your Mac using sudo reboot now.
Another hint on this is that the shutdown dialog still shows up if you press the shutdown button for 2-3 seconds.
This might also be a hint to the solution - it should suffice to restart the corresponding process, even though I don't know which one that is. Maybe someone with a little more expertise on the OS might be able to help here.

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