How to fix SystemError: access denied (operating system rejected operation) in Node.js

# Use Resource Monitor to find processes using the file
# Press Win+R, type "resmon", go to CPU tab, search for filename in "Associated Handles"

# Or use PowerShell:
$file = "C:\path\to\file.txt"
Get-Process | ForEach-Object { $_.Modules } | Where-Object { $_.FileName -eq $file }

# List processes using the file
lsof /path/to/file.txt

# Or find which process is accessing a directory
lsof +D /path/to/directory

# View file permissions
icacls "C:\path\to\file.txt"

# Grant full control to current user
icacls "C:\path\to\file.txt" /grant "%USERNAME%":F

# Check file permissions
ls -la /path/to/file.txt

# Check directory permissions (need write permission on directory to create/delete files)
ls -ld /path/to/directory

# Fix permissions if needed
sudo chown $USER:$USER /path/to/file.txt
chmod 644 /path/to/file.txt  # rw-r--r--
chmod 755 /path/to/directory  # rwxr-xr-x

# Add folder exclusion
Add-MpPreference -ExclusionPath "C:\path\to\project"

# Or via GUI: Windows Security → Virus & threat protection → Manage settings → Add exclusions

const fs = require('fs').promises;

async function writeFileWithRetry(path, data, maxRetries = 5) {
  for (let i = 0; i < maxRetries; i++) {
    try {
      await fs.writeFile(path, data);
      return; // Success
    } catch (error) {
      if (error.message?.includes('access denied') || 
          error.message?.includes('operation was rejected')) {
        if (i === maxRetries - 1) throw error; // Last attempt failed
        
        // Exponential backoff: 100ms, 200ms, 400ms, 800ms, 1600ms
        const delay = 100 * Math.pow(2, i);
        console.log(`Retry ${i + 1}/${maxRetries} after ${delay}ms...`);
        await new Promise(resolve => setTimeout(resolve, delay));
      } else {
        throw error; // Not a locking error, fail immediately
      }
    }
  }
}

// Usage
try {
  await writeFileWithRetry('./output.txt', 'data');
  console.log('File written successfully');
} catch (error) {
  console.error('Failed after retries:', error.message);
}

# Right-click Command Prompt or PowerShell, select "Run as administrator"
# Then run your Node.js script
node your-script.js

# Or use runas command
runas /user:Administrator "node your-script.js"

# Run with sudo (use cautiously)
sudo node your-script.js

# Better: Fix ownership instead of using sudo
sudo chown -R $USER:$USER /path/to/directory

# Check if file is read-only
attrib "C:\path\to\file.txt"

# Remove read-only attribute
attrib -R "C:\path\to\file.txt"

# Check if disk is mounted read-only (rare on Windows)
mountvol

# Check filesystem mount status
mount | grep /path/to/filesystem

# If mounted read-only, remount as read-write (requires root)
sudo mount -o remount,rw /path/to/filesystem

# Check for immutable flag
lsattr /path/to/file.txt

# Remove immutable flag if set (requires root)
sudo chattr -i /path/to/file.txt