How to fix npm ERR! code EPERM npm ERR! Operation not permitted - possibly blocked by antivirus in npm

This is the safest solution as it prevents antivirus from interfering without disabling security entirely.

For Windows Defender:

1. Open Windows Security by pressing Windows Key + I to open Settings
2. Go to Virus & threat protection > Manage settings
3. Under "Exclusions," click Add or remove exclusions
4. Click Add an exclusion and choose Folder
5. Browse to and select your project directory (e.g., C:\Users\YourName\Projects\my-app)
6. Repeat for your npm global folder (typically C:\Users\YourName\AppData\Roaming\npm)
7. Close Windows Security

Now retry your npm install:

npm install

If adding folder exclusions doesn't resolve the issue, temporarily disable real-time scanning for a single npm install session.

For Windows Defender:

1. Open Windows Security (Windows Key + I > Virus & threat protection)
2. Click Manage settings
3. Under "Real-time protection," toggle the switch to Off
4. Open Command Prompt or PowerShell and run:

npm install

5. Once npm install completes successfully, turn real-time protection back On in Windows Security

Note: Only disable protection temporarily during the npm install—keep your antivirus running for ongoing system protection.

Sometimes npm's cache can become corrupted or locked by antivirus. Clearing the cache and starting fresh often resolves the issue:

# Stop any running npm processes or development servers first

# Clear npm cache
npm cache clean --force
npm cache verify

# Delete the corrupted node_modules folder
rm -r node_modules
# On Windows PowerShell:
# Remove-Item -Recurse -Force node_modules

# Delete package-lock.json to force a fresh lock file
rm package-lock.json

# Reinstall dependencies
npm install

Windows antivirus sometimes blocks file operations for non-admin processes. Elevating privileges can allow npm to complete:

1. Right-click Command Prompt or PowerShell and select Run as administrator
2. Navigate to your project directory:

cd C:\Users\YourName\Projects\my-app

3. Run npm install:

npm install

The "Run as administrator" window title will show "Administrator" to confirm elevation.

Beyond your project folder, npm has a global configuration directory and cache. Antivirus scanning these locations can also trigger EPERM errors.

First, find your npm directories:

npm config get prefix     # Shows global npm location
npm config get cache      # Shows cache location

On Windows, these are typically:
- Global modules: C:\Users\YourName\AppData\Roaming\npm
- Cache: C:\Users\YourName\AppData\Local\npm-cache

Add both directories to your antivirus exclusions (see Step 1 for instructions).

Visual Studio Code, WebStorm, and other editors may lock files in your project, which antivirus can interpret as permission issues:

1. Close all instances of your IDE (VS Code, WebStorm, Sublime, etc.)
2. Stop any running development servers (webpack-dev-server, Next.js dev server, etc.)
3. Open a fresh Command Prompt or PowerShell (not integrated into an IDE)
4. Navigate to your project and run:

npm install

5. Once npm completes successfully, reopen your IDE