Peer Dependency Conflict npm Error (2026)

The Error

npm ERR! code ERESOLVE
npm ERR! ERESOLVE unable to resolve dependency tree
npm ERR! peer react@"^17.0.0" from some-component@2.1.0
npm ERR! node_modules/some-component
npm ERR!   some-component@"^2.1.0" from the root project
npm ERR! Could not resolve dependency:
npm ERR! peer react@"^17.0.0" from some-component@2.1.0
npm ERR! Conflicting peer dependency: react@17.0.2

This error occurs when Claude adds a dependency that requires a different version of a peer dependency than what your project uses.

The Fix

  1. Check what version you have vs what is required:
npm ls react
  1. Try installing with legacy peer deps (quick fix):
npm install --legacy-peer-deps
  1. Better: update the conflicting package to a version compatible with your React:
npm install some-component@latest
  1. Verify no conflicts remain:
npm ls --all 2>&1 | grep "ERESOLVE\|peer dep\|invalid"

Why This Happens

npm v7+ enforces strict peer dependency resolution by default. When package A requires react@^17 but your project uses react@18, npm refuses to install because it cannot satisfy both constraints. Claude adds dependencies based on functionality without checking peer dependency compatibility against your existing packages.

If That Doesn’t Work

  • Force the installation (use with caution):
npm install --force
  • Use pnpm which handles peer deps more gracefully:
npm install -g pnpm
pnpm import  # Convert from npm
pnpm install
  • Pin the overriding version in package.json:
{
  "overrides": {
    "react": "^18.0.0"
  }
}

Prevention

Add this to your CLAUDE.md:

# Dependencies
- Check peer dependencies before adding packages: npm info PACKAGE peerDependencies
- Use overrides in package.json to resolve peer conflicts.
- Prefer packages that support our React/Next.js version.
- Run npm ls after every install to catch conflicts early.

See Also

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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