Nodemon Error: System limit for number of file watchers reached

If you are using Linux, your project is hitting your system's file watchers limit

To fix this, on your terminal, try:

echo fs.inotify.max_user_watches=524288 | sudo tee -a /etc/sysctl.conf && sudo sysctl -p

I sometimes get this issue when working with VSCode on my Ubuntu machine.

In my case the following workaround helps:

stop the watcher, close VScode, start the watcher, open VSCode again.

You need to increase the inotify watchers limit for users of your system. You can do this from the command line with:

sudo sysctl -w fs.inotify.max_user_watches=100000

That will persist only until you reboot, though. To make this permanent, add a file named /etc/sysctl.d/10-user-watches.conf with the following contents:

fs.inotify.max_user_watches = 100000

After making the above (or any other) change, you can reload the settings from all sysctl configuration files in /etc with sudo sysctl -p.

In order to test the changes, I set temporary the parameter with the value 524288.

sysctl -w fs.inotify.max_user_watches=524288

then I proceed to validate :

npm run serve

And the problem was solved, in order to make it permanent, you should try to add a line in the file "/etc/sysctl.conf" and then restart the sysctl service :

cat /etc/sysctl.conf |tail -n 2
fs.inotify.max_user_watches=524288

sudo systemctl restart systemd-sysctl.service

I had the same problem, however mine was coming from webpack. Thankfully they hd a great solution on their site:

For some systems, watching many files can result in a lot of CPU or memory usage. It is possible to exclude a huge folder like node_modules using a regular expression:

webpack.config.js

module.exports = {
  watchOptions: {
    ignored: /node_modules/
  }
};

This is A problem of inotify (inode notify) is a Linux kernel so you can resolve by using Command

1. temporary solution until reboot the pc use following command

sudo sysctl -w fs.inotify.max_user_watches=100000

2. permonant solution To make this permanent, add a file named /etc/sysctl.d/10-user-watches.conf with the following contents:

fs.inotify.max_user_watches = 10000

After making change, reload the setttings from all sysctl configuration files in /etc with sudo sysctl -p.

It can be hard to know how much to increase the number of watchers by. So, here's a utility to double the number of watchers:

function get_inode_watcher_count() {
  find /proc/*/fd -user "$USER" -lname anon_inode:inotify -printf '%hinfo/%f\n' 2>/dev/null | 
  xargs cat | 
  grep -c '^inotify'
}

function set_inode_watchers() {
  sudo sysctl -w fs.inotify.max_user_watches="$1"
}

function double_inode_watchers() {
  watcher_count="$(get_inode_watcher_count)"
  set_inode_watchers "$((watcher_count * 2))"

  if test "$1" = "-p" || test "$1" = "--persist"; then
    echo "fs.inotify.max_user_watches = $((watcher_count * 2))" > /etc/sysctl.d/10-user-watches.conf
  fi
}

# Usage
double_inode_watchers
# to make the change persistent
double_inode_watchers --persist

In my case, while I'm doing the nodemon command in the Linux server. I have my VSCode open (SSH to the server). So based on @Juri Sinitson's answer, I just close the VSCode and run the nodemon command again. And it works.

My nodemon command: nodemon server.js via npm start

I think most answers given here are correct but what solved the problem for me was, using the systemctl command to restart my service, check the command below

sudo systemctl restart systemd-sysctl.service

On Linux, I've actually run with sudo. sudo npm start