Jtdylktuy

According to this helpful article (which I recommend reading):

By default, the maximum number of files that Mac OS X can open is set
to 12,288 and the maximum number of files a given process can open is
10,240.

You can check these with:

• sysctl kern.maxfiles


• sysctl kern.maxfilesperproc

You can increase the limits (at your own risk) with:

• 
  sysctl -w kern.maxfiles=20480 (or whatever number you choose)


• 
  sysctl -w kern.maxfilesperproc=18000 (or whatever number you choose)

To make the change permanent, use sudo to put your settings in /etc/sysctl.conf (which you may have to create), like this:

kern.maxfiles=20480

kern.maxfilesperproc=18000

^{Note: In OS X 10.10 or lower, you can add setting in /etc/launchd.conf like limit maxfiles and it will override whatever you put here.}

Again, from the article:

Once you’ve done this, the kernel itself will have a maximum number of
files but the shell might not. And since most processes that will take
up this many files are going to be initiated by the shell you’re
gonna want to increase that.

The command for that is:

ulimit -S -n 2048 # or whatever number you choose

That change is also temporary; it only lasts for the current shell session. You can add it to your shell configuration file (.bashrc, .zshrc or whatever) if you want it to run every time you open a shell.

It seems like there is an entirely different method for changing the open files limit for each version of OS X!

For OS X Sierra (10.12.X) you need to:

1.
Create a file at /Library/LaunchDaemons/limit.maxfiles.plist and paste the following in (feel free to change the two numbers (which are the soft and hard limits, respectively):

<?xml version="1.0" encoding="UTF-8"?>  

<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"  

        "http://www.apple.com/DTDs/PropertyList-1.0.dtd">

<plist version="1.0">  

  <dict>

    <key>Label</key>

    <string>limit.maxfiles</string>

    <key>ProgramArguments</key>

    <array>

      <string>launchctl</string>

      <string>limit</string>

      <string>maxfiles</string>

      <string>64000</string>

      <string>524288</string>

    </array>

    <key>RunAtLoad</key>

    <true/>

    <key>ServiceIPC</key>

    <false/>

  </dict>

</plist> 

2.
Change the owner of your new file:

sudo chown root:wheel /Library/LaunchDaemons/limit.maxfiles.plist

3.
Load these new settings:

sudo launchctl load -w /Library/LaunchDaemons/limit.maxfiles.plist

4.
Finally, check that the limits are correct:

launchctl limit maxfiles

You will need to increase your ulimit settings - it's pretty low on OS X these days - 256 by default. Add ulimit -n 4096 or similar to your ~/.profile or equivalent and that will solve it in your local environment. Run ulimit -a to check your current levels

To see the system settings, run this:

launchctl limit maxfiles

It is set quite a bit higher in Lion (10240) on a per process basis than it used to be. But if you are still hitting it there then you can set it higher using the same command with the desired levels. To make the changes permanent /etc/launchd.conf is where you need to add the relevant lines.

Other option may be finding the culprit:

sudo lsof -n | cut -f1 -d' ' | uniq -c | sort | tail

For the last one you could see what files are open:

sudo lsof -n | grep socketfil

And kill the process if so desired

kill $pid

From the comments:

For what it's worth, you can also get a list of the process IDs with the most open files using

lsof -n | sed -E 's/^[^ ]+[ ]+([^ ]+).*$/1/' | uniq -c | sort | tail

Folks, on Mavericks 10.9.4

ulimit -n 2048 works fine. You may need to launch a new login session.

You can run

lsof -n

which process open too many files.

then kill it .

or

sysctl -w kern.maxfiles=20480

change it to bigger one.

I encountered it while doing a chmod -R so I got it around by taking smaller steps, e.g.

# for each directory

find . -type d -exec chmod 755 {} ;

For latest macOS (at the time of writing: 10.14.1), you can use sudo launchctl limit maxfiles 64000 524288 (by default it was 256), but it works only within current session. Use launchctl job from @ninjaPixel (https://superuser.com/a/1171028/760235) for permanent solution.