I'm unable to kill a process using any of the techniques I'm aware of ("Force Quit" in Activity Monitor, top, killall from the Terminal) and wonder if there are some additional steps I can take.

enter image description here

~ $ sudo killall -KILL 77439
No matching processes were found
~ $ killall -KILL 77439
No matching processes belonging to you were found
~ $ killall 77439
No matching processes belonging to you were found
~ $ killall Mathematica
No matching processes belonging to you were found

FWIW the process is "Mathematica" which I cannot relaunch, Quit, or Force Quit, or sample, either by name or PID, and it appears to have some odd side effects (screenshots don't appear, can't empty trash, and can't even shut down the system).

Are there additional steps that can be taken to really really kill a badly behaved process?

  • Can you find this process using top in the terminal? – Pierobon Feb 1 '14 at 19:03
  • 1
    Next time this problem does occur, please add the output of ps alx | egrep '[ /](PID|Math)' to your question. – dan Feb 1 '14 at 20:25
  • @danielAzuelos: Good tip. Will do. – orome Feb 1 '14 at 20:31

killall kills by process name (which is definitively not 77439 and most probably also not Mathematica). You can use kill 77439 or (if this fails) kill -9 77439 instead (but if the process is really stuck, only a reboot will solve the problem).

Also, due the the way sending/processing of signals (like kill -9) works in Unix/OS X, there are situations where a process will be unkillable. One typical example for this is if a process gets stuck while accessing some external device and never actually gets control back. In such situations a reboot is the only way to get rid of the process.

  • 2
    Kill sounds like it should go just as it says, but really it should be called 'send interrupt signal', as there are many different types of kill it can perform. Using the parameters -9 essentially uses the most powerful form of terminating with extreme predjudice available... – stuffe Feb 1 '14 at 18:14
  • 1
    $kill -9 PID always does the trick for me, even if it's that much invasive. – Pierobon Feb 1 '14 at 19:05
  • So it seems like Mathematica is just unusually badly behaved. In the end I had to force shutdown (regular shutdown hung). I don't have this problem with any other app, but Mathematica has had it more than once. – orome Feb 1 '14 at 19:09
  • 1
    Here are some more details about what can cause processes to get stuck. – GDP2 Jan 9 '18 at 20:41
  • I'll second kill -9. The only time I have had a "sudo kill -9" fail was on a system that was completely borked and needed rebooted anyway. – MikeP Sep 7 '18 at 19:55

Sometimes killing the parental process can get rid of an otherwise unkillable process. Unfortunately, if the parental process is PID 0 or 1 (launchd) you are pretty screwed.

Find the parental process in Activity Monitor.


On newer os, use launchctl to trigger a reboot of the apps / user space.

launchctl reboot apps
launchctl reboot logout
sudo launchctl reboot userspace

I would start with apps after saving your work, then progress to a logout and then the userspace reboot. You shouldn’t need to restart the entire OS unless things are really broken far past one stuck process. Stop as soon as the first one of the above commands gives you relief.


Running macOS Mojave 10.14 Beta 1, I had to run the following to get any traction:

sudo xcscontrol --reset   
  • 3
    What exactly does this do / why is it needed? – pkamb Nov 1 '18 at 22:06
  • xcscontrol is Xcode Server Control, and doesn't seem to have any correlation to a badly behaved process? – Matt Sephton Mar 13 '19 at 16:36
  • I've got this on running the command: Failed: Current Xcode symlink (/Library/Developer/XcodeServer/CurrentXcodeSymlink) not found, service doesn't appear to be configured. – Vladyn Jul 27 '20 at 4:02

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .