🔧 Fix: "Too Many Open Files" Error (EMFILE)

🚨 The Problem

You're seeing this error in Git logs:

EMFILE: too many open files, open '/Users/fguijarro/developer/repos/editor/.git/HEAD'
EMFILE: too many open files, open '/Users/fguijarro/developer/repos/editor/.git/config'

Root Cause: macOS limits file descriptors to 256 by default, which is too low for multiple monorepos.

Current limits:

$ launchctl limit maxfiles
maxfiles    256            unlimited
#           ^^^
#           This is too low!

✅ The Solution

We need to increase macOS file descriptor limits to support multiple monorepos.

Step 1: Apply Immediate Fix (Current Session)

Run this command in your terminal:

sudo launchctl limit maxfiles 65536 200000

Enter your password when prompted.

This increases:

• Soft limit: 256 → 65,536
• Hard limit: unlimited → 200,000

Verify:

launchctl limit maxfiles
# Should show: maxfiles    65536          200000

Step 2: Make It Permanent (Survives Reboots)

The LaunchAgent file has already been created at: ~/Library/LaunchAgents/limit.maxfiles.plist

Load it now:

launchctl load -w ~/Library/LaunchAgents/limit.maxfiles.plist

Verify it's loaded:

launchctl list | grep limit.maxfiles

Step 3: Update Your Shell Configuration

Add to your ~/.zshrc (already has multi-monorepo config):

# Add this to the multi-monorepo section
ulimit -n 65536

Quick command:

echo "" >> ~/.zshrc
echo "# Increase file descriptor limit for multi-monorepo development" >> ~/.zshrc
echo "ulimit -n 65536" >> ~/.zshrc
source ~/.zshrc

Verify:

ulimit -n
# Should show: 65536

Step 4: Restart Cursor

Important: Cursor needs to be restarted to pick up the new limits.

1. Completely quit Cursor (⌘ + Q)
2. Wait 10 seconds
3. Reopen Cursor

🧪 Testing & Verification

Test 1: Check System Limits

launchctl limit maxfiles
# Expected: maxfiles    65536          200000

Test 2: Check Shell Limits

ulimit -n
# Expected: 65536

Test 3: Check Cursor Git Operations

1. Open any monorepo in Cursor
2. Check Git panel
3. Make a change and check Git status
4. Should NOT see "EMFILE" errors

Test 4: Monitor Open Files

# Check how many files Cursor has open (run while Cursor is running)
lsof -c Cursor | wc -l

📊 Why These Numbers?

Your setup:

• 3 monorepos × ~10,000 files each = ~30,000 files
• File watchers, Git operations, language servers = +20,000
• Buffer for growth = +15,000
• Total needed: ~65,000

🔄 Rollback (If Needed)

Remove the limit increase:

# Unload LaunchAgent
launchctl unload -w ~/Library/LaunchAgents/limit.maxfiles.plist

# Remove the file
rm ~/Library/LaunchAgents/limit.maxfiles.plist

# Reset to system defaults
sudo launchctl limit maxfiles 256 unlimited

# Remove from .zshrc
# Edit ~/.zshrc and remove the "ulimit -n 65536" line

🆘 Troubleshooting

Issue: "Operation not permitted"

Solution:

# Give Terminal/Cursor Full Disk Access
# System Preferences → Privacy & Security → Full Disk Access
# Add Terminal.app and Cursor.app

Issue: Changes don't persist after reboot

Solution:

# Verify LaunchAgent is loaded
launchctl list | grep limit.maxfiles

# If not loaded, load it again
launchctl load -w ~/Library/LaunchAgents/limit.maxfiles.plist

Issue: Still seeing EMFILE errors in Cursor

Solution:

# 1. Verify limits are applied
launchctl limit maxfiles

# 2. Completely restart Cursor
killall Cursor
# Wait 10 seconds, then reopen

# 3. Check if file watchers are excessive
# Disable unused file watchers in .vscode/settings.json

Issue: Limits show but still failing

Solution - Increase even more:

# For very large monorepos
sudo launchctl limit maxfiles 100000 300000

# Update LaunchAgent plist
# Edit ~/Library/LaunchAgents/limit.maxfiles.plist
# Change to: <string>100000</string> <string>300000</string>

# Reload
launchctl unload -w ~/Library/LaunchAgents/limit.maxfiles.plist
launchctl load -w ~/Library/LaunchAgents/limit.maxfiles.plist

📋 Quick Commands Summary

# === APPLY FIX ===

# 1. Increase limits now (requires password)
sudo launchctl limit maxfiles 65536 200000

# 2. Add to shell
echo "ulimit -n 65536" >> ~/.zshrc && source ~/.zshrc

# 3. Load LaunchAgent (permanent)
launchctl load -w ~/Library/LaunchAgents/limit.maxfiles.plist

# 4. Verify
launchctl limit maxfiles
ulimit -n

# 5. Restart Cursor


# === VERIFY ===

# Check system limits
launchctl limit maxfiles

# Check shell limits
ulimit -n

# Check what's using files
lsof | wc -l

# Monitor Cursor's open files
lsof -c Cursor | wc -l


# === ROLLBACK ===

launchctl unload -w ~/Library/LaunchAgents/limit.maxfiles.plist
rm ~/Library/LaunchAgents/limit.maxfiles.plist
sudo launchctl limit maxfiles 256 unlimited
# Remove "ulimit -n 65536" from ~/.zshrc

🎯 Integration with Multi-Monorepo Setup

This fix is required for the multi-monorepo configuration to work properly. Add it to your startup checklist:

1. ✅ Multi-monorepo Node.js configuration (from ADD_TO_ZSHRC.txt)
2. ✅ File descriptor limits (this fix)
3. ✅ Cursor optimizations (.vscode/settings.json)
4. ✅ Nx configuration (nx.json)

📝 Technical Details

What are file descriptors?

File descriptors are handles to open files, sockets, pipes, etc. Every:

• File being watched for changes
• Git operation
• Network connection
• Language server process
• Terminal session

...uses one or more file descriptors.

Why does macOS limit them?

• Security: Prevent runaway processes
• Stability: Limit resource consumption
• Legacy: Default of 256 is from older macOS versions

Why 65,536?

• Standard high limit on Unix systems
• Sufficient for multiple monorepos
• Low enough to not cause other issues
• Matches Linux typical limits

Created: October 18, 2025
Last Updated: October 18, 2025
Applies To: macOS (all versions)
Required For: Multi-monorepo development