Fix EACCES Permission Errors During npm Install in Claude Code

The Problem

Claude Code runs npm install and hits a permission error:

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

Quick Fix

For local project installs, fix the node_modules ownership:

sudo chown -R $(whoami) node_modules/
npm install

For global install permission issues, configure npm to use a user-owned directory:

mkdir -p ~/.npm-global
npm config set prefix '~/.npm-global'
echo 'export PATH=~/.npm-global/bin:$PATH' >> ~/.zshrc
source ~/.zshrc

What Is Happening

EACCES errors occur when the current user lacks write permission to a directory that npm needs to modify. This happens in three common scenarios:

1. Previous sudo install: Someone ran sudo npm install and now root owns files inside node_modules/.
2. Global prefix pointing to system directory: npm's default global prefix (/usr/local) requires root access.
3. Corrupted npm cache: The npm cache directory has mixed ownership from previous sudo operations.

Step-by-Step Fix

Step 1: Diagnose the exact cause

npm install 2>&1
ls -la node_modules/ | head -20

Step 2: Fix node_modules ownership

# Check for root-owned files
find node_modules/ -user root -type f | head -10

# Fix ownership recursively
sudo chown -R $(whoami):$(id -gn) node_modules/

# Now install normally
npm install

Step 3: Fix global prefix

mkdir -p ~/.npm-global
npm config set prefix '~/.npm-global'
echo 'export PATH=~/.npm-global/bin:$PATH' >> ~/.zshrc
source ~/.zshrc
npm config get prefix
# Should output: /Users/you/.npm-global

Step 4: Fix npm cache permissions

sudo chown -R $(whoami):$(id -gn) ~/.npm
# Or clean the cache entirely
npm cache clean --force

Using pnpm Instead

pnpm avoids most EACCES issues because it uses a content-addressable store in user space:

npm install -g pnpm
pnpm install

Prevention

Never run sudo npm install for local project dependencies. If a tutorial tells you to use sudo with npm, the correct fix is always to change ownership or the global prefix. Add a .npmrc file to your project root for consistent behavior:

engine-strict=true
save-exact=true
fund=false
audit=false