Too many open files — how to fix

Error: EMFILE: too many open files, watch '/home/me/app/src'
OSError: [Errno 24] Too many open files
accept4: too many open files

Quick fix: Check the limit with ulimit -n. Raise it for the session: ulimit -n 65535; for services set LimitNOFILE=65535 in the systemd unit. For EMFILE ... watch errors from dev servers, raise fs.inotify.max_user_watches.

What it means

Every open file, socket, pipe and watcher uses a file descriptor. Each process has a limit (often 1024 soft by default). Error code EMFILE / Errno 24 means the process reached it.

Check current limits and usage:

ulimit -Sn; ulimit -Hn            # soft / hard limit for this shell
cat /proc/<PID>/limits | grep files
ls /proc/<PID>/fd | wc -l          # how many are open now

Fix 1: raise the limit for your shell

ulimit -n 65535     # up to the hard limit

Permanent for user logins, in /etc/security/limits.conf:

*   soft  nofile  65535
*   hard  nofile  65535

Log out and back in.

Fix 2: services under systemd

limits.conf does not apply to systemd services. Add an override:

sudo systemctl edit myapp

[Service]
LimitNOFILE=65535

sudo systemctl restart myapp

For Docker containers: docker run --ulimit nofile=65535:65535 ....

Fix 3: file watchers (EMFILE: watch, ENOSPC: System limit for number of file watchers reached)

Node dev servers (webpack, Vite, Jest, nodemon) and IDEs use inotify watches:

echo "fs.inotify.max_user_watches=524288" | sudo tee /etc/sysctl.d/99-inotify.conf
echo "fs.inotify.max_user_instances=512" | sudo tee -a /etc/sysctl.d/99-inotify.conf
sudo sysctl --system

Also exclude node_modules and build folders from watching.

On macOS, EMFILE with watchers is often fixed by installing watchman (brew install watchman).

Fix 4: the code leaks descriptors

If the count in /proc/<PID>/fd keeps growing, something isn't being closed. Check with lsof -p <PID>. Use context managers / finally blocks:

with open(path) as f:
    data = f.read()

Reuse HTTP clients and DB connection pools instead of creating new ones per request.

Last updated 2026-10-27.