Fix npm "EACCES: permission denied"

npm ERR! code EACCES
npm ERR! syscall mkdir
npm ERR! path /usr/local/lib/node_modules/typescript
npm ERR! errno -13
npm ERR! Error: EACCES: permission denied, mkdir '/usr/local/lib/node_modules/typescript'

Common causes

• Global installs (npm install -g) into /usr/local/lib/node_modules, which belongs to root when Node came from a system package or installer
• An earlier sudo npm command left root-owned files in ~/.npm
• node_modules or package-lock.json in the project was created by sudo npm install or inside a Docker container as root
• The project folder is on a mount or share where your user lacks write permission
• Running npm in CI or Docker as a non-root user against files copied in as root

How to fix it

1. Fix a root-owned cache. If the path is under ~/.npm, run sudo chown -R $(id -u):$(id -g) ~/.npm. This is the fix npm itself suggests for 'Your cache folder contains root-owned files'.
2. Fix the project folder. If the path is inside your project, run sudo chown -R $(id -u):$(id -g) node_modules package-lock.json, or delete node_modules and reinstall with plain npm install.
3. Install Node with a version manager. Install nvm (or fnm/Volta) and run nvm install --lts. Node and its global packages then live in your home folder, so npm install -g never needs sudo.
4. Or set a user-owned global prefix. Run mkdir -p ~/.npm-global and npm config set prefix ~/.npm-global, then add export PATH=~/.npm-global/bin:$PATH to ~/.bashrc or ~/.zshrc and open a new shell.
5. Use the right user in Docker. Set USER node before npm install in the Dockerfile and copy files with COPY --chown=node:node . . so the container user owns the app folder.

Terminal

# root-owned cache
sudo chown -R $(id -u):$(id -g) ~/.npm

# user-owned global folder (alternative to nvm)
mkdir -p ~/.npm-global
npm config set prefix ~/.npm-global
echo 'export PATH=~/.npm-global/bin:$PATH' >> ~/.bashrc
source ~/.bashrc

How to stop it happening again

• Never run sudo npm install, globally or in a project
• Manage Node with nvm, fnm or Volta on developer machines
• Use npx for one-off CLIs instead of installing them globally
• Run containers and CI jobs as the same user that owns the files