React Native Error: EMFILE – Too Many Open Files and Solution

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Introduction

While working on a React Native project, you might encounter the following error during development or when bundling the application:

Error: EMFILE: too many open files, watch
    at FSWatcher._handle.onchange (node:internal/fs/watchers:207:21)
Emitted 'error' event on NodeWatcher instance at:
    at FSWatcher._checkedEmitError (/path/to/project/node_modules/metro-file-map/src/watchers/NodeWatcher.js:82:12)

This error typically occurs when too many file watchers are active, exhausting system resources.

Cause

The error happens due to:

  1. Watchman Overload: Watchman, used to monitor file changes, exceeds its limits.
  2. File Descriptor Limits: Your system’s file descriptor limit is too low to handle the number of files being watched.

Solution

Here’s how to resolve the issue step-by-step:

Step 1: Clear Watchman Watches

Run the following command to clear all active Watchman file watchers:

watchman watch-del-all
Step 2: Rebundle the Application

After clearing Watchman, regenerate the required main.jsbundle for iOS:

npx react-native bundle --platform ios --dev false --entry-file index.js --bundle-output ./ios/main.jsbundle
Step 3: Increase File Descriptor Limit (Optional)

MacOs:

If the issue persists, increase your system’s file descriptor limit:

ulimit -n 8192

Reload the file:

source ~/.zshrc

Conclusion

By following these steps, you should resolve the EMFILE: too many open files error and successfully bundle your React Native project for iOS.