Can't fork process: Resource temporarily unavailable issue

Question

I've got a problems with using terminal on macOS 10.12.3 on Mac mini

When I try to run any command I get the following message:

can't fork process: Resource temporarily unavailable.

I have already had such problem. Last time I was able to fix it - increase the number of process and my system looked like:

sysctl -a | grep maxproc  
kern.maxproc: 2048  
kern.maxprocperuid: 2048  


ulimit -a  
core file size          (blocks, -c) 0  
data seg size           (kbytes, -d) unlimited  
file size               (blocks, -f) unlimited  
max locked memory       (kbytes, -l) unlimited  
max memory size         (kbytes, -m) unlimited  
open files                      (-n) 65536  
pipe size            (512 bytes, -p) 1  
stack size              (kbytes, -s) 8192  
cpu time               (seconds, -t) unlimited  
max user processes              (-u) 2048  
virtual memory          (kbytes, -v) unlimited  

I thought that the problem was solved, but now I had that issue once again.

I was able to solve this problem this time with reboot - but it's strongly undesireable to reboot my mac every time.

Do you have any advise how to fix that problem once and for all?

Answer 1

No idea why your question was downvoted…

---

sudo sysctl kern.tty.ptmx_max=255 (or 511, or whatever) should fix it.

My default (in El Capitan) was 127. (As a tmux user, I need more than that.)

To learn more:

sysctl -a | grep max
ulimit -a
launchctl limit

cat /private/etc/launchd.conf
cat /private/etc/sysctl.conf

man 8 sysctl

Answer 2

Rebooting solves the issue. In my case, I opened Activity Monitor and found way too many processes for "Outlook WebContent". I quit MS Outlook and voila, the terminal reopened and that error disappeared.