Claude Code pnpm Lock File Out of Sync (2026)

The Error

 ERR_PNPM_OUTDATED_LOCKFILE  Cannot install with "frozen-lockfile" because
  pnpm-lock.yaml is not up to date with package.json.
Note that in CI environments this setting is turned on by default.
# Or:
 ERR_PNPM_LOCKFILE_BREAKING_CHANGE  Lockfile /path/pnpm-lock.yaml not
  compatible with current pnpm version. Please delete it and run pnpm install.
# Or:
Lockfile is up to date, but some packages are missing.
  Run pnpm install to install them.

The Fix

  1. Regenerate the lock file from package.json
# Remove existing lock and node_modules
rm pnpm-lock.yaml
rm -rf node_modules
# Reinstall everything
pnpm install
# Verify lock file was created
ls -la pnpm-lock.yaml
  1. If the issue is a pnpm version mismatch
# Check pnpm version
pnpm --version
# Check required version in package.json
cat package.json | python3 -c "import sys,json; print(json.load(sys.stdin).get('packageManager','not set'))"
# Install the required version with corepack
corepack enable
corepack prepare pnpm@9.15.0 --activate
pnpm install
  1. Verify the fix:
pnpm install --frozen-lockfile
# Expected: No errors — lockfile matches package.json exactly

Why This Happens

The pnpm-lock.yaml file is a snapshot of the exact dependency tree. When Claude Code modifies package.json (adding, removing, or updating dependencies) without running pnpm install afterward, the lock file becomes stale. Running pnpm install --frozen-lockfile (the CI default) then fails because it refuses to modify the lock file. Additionally, pnpm lock file format versions change between major pnpm releases — a lock file created with pnpm 8 may be incompatible with pnpm 9.

If That Doesn’t Work

  • Alternative 1: Use pnpm install --no-frozen-lockfile to update the lock file in place without deleting it
  • Alternative 2: If merge conflicts corrupted the lock file: git checkout main -- pnpm-lock.yaml && pnpm install
  • Check: Run pnpm why <package-name> to trace dependency resolution and find version conflicts

Prevention

Add to your CLAUDE.md:

After modifying any package.json, always run `pnpm install` to update pnpm-lock.yaml. Commit the updated lock file with the package.json change. Pin pnpm version in package.json "packageManager" field. Never manually edit pnpm-lock.yaml.

Related articles: Monorepo Setup Guide, NPM Install Fails Fix, Troubleshooting Hub

This fix also applies if you see variations of this error:

  • Connection or process errors with similar root causes in the same subsystem
  • Timeout variants where the operation starts but does not complete
  • Permission variants where access is denied to the same resource
  • Configuration variants where the same setting is missing or malformed

If your specific error message differs slightly from the one shown above, the fix is likely the same. The key indicator is the operation that failed (shown in the stack trace) rather than the exact wording of the message.

Frequently Asked Questions

Does this error affect all operating systems?

This error can occur on macOS, Linux, and Windows (WSL). The exact error message may differ slightly between platforms, but the root cause and fix are the same. macOS users may see additional Gatekeeper or notarization prompts. Linux users should check that the relevant system packages are installed. Windows users should ensure they are running inside WSL2, not native Windows.

Will this error come back after updating Claude Code?

Updates can occasionally reintroduce this error if the update changes default configurations or dependency requirements. After updating Claude Code, verify your project still builds and runs correctly. If the error returns, reapply the fix and check the changelog for breaking changes.

Can this error cause data loss?

No, this error occurs before or during an operation and does not corrupt existing files. Claude Code’s edit operations are atomic — they either complete fully or not at all. However, if the error occurs during a multi-step operation, you may have partial changes that need to be reviewed with git diff before continuing.

How do I report this error to Anthropic if the fix does not work?

Open an issue at github.com/anthropics/claude-code with: (1) the full error message including stack trace, (2) your Node.js version (node --version), (3) your Claude Code version (claude --version), (4) your operating system and version, and (5) the command or operation that triggered the error.

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