npm reported an ERESOLVE peer-dependency conflict in…

Error message

npm reported an ERESOLVE peer-dependency conflict in marketplace deps; retrying once with --legacy-peer-deps.

What it means

The installer runs a strict `npm install` in the marketplace directory. When it fails with an ERESOLVE peer-dependency conflict, the installer logs this warning, prints the extracted ERESOLVE block, and retries exactly once with `--legacy-peer-deps` (which skips peer-resolution enforcement).

Solutions

Let the installer's automatic --legacy-peer-deps retry complete — it usually resolves the conflict.
Run `npm install --legacy-peer-deps` manually inside the marketplace directory to inspect/fix the tree.
Update or remove the offending plugin package whose peerDependencies conflict, then rerun the installer.
Use an npm override in package.json to force a compatible peer version.

Example fix

// before
npm install
// after
npm install --legacy-peer-deps

Defensive patterns

Strategy: retry

Validate before calling

npm ls --all 2>&1 | grep -i 'ERESOLVE\|peer' || echo 'peer deps OK'

Try / catch

try {
  runNpmStrict(marketplaceDir, baseFlags);
} catch (e) {
  if (String(e.details).includes('ERESOLVE')) {
    runNpmStrict(marketplaceDir, [...baseFlags, '--legacy-peer-deps']);
  } else { throw e; }
}

Prevention

Pre-install with --legacy-peer-deps when marketplace plugins pin conflicting peer versions.
Keep plugin packages updated so peerDependency ranges stay compatible.
Use npm overrides in package.json to pin shared deps to a single compatible version.

When it happens

Trigger: `runNpmStrict(marketplaceDir, baseFlags)` exits non-zero with stderr containing an ERESOLVE block — e.g. marketplace plugin packages demanding incompatible peer versions of a shared dependency.

Common situations: Plugins in the marketplace pinning peerDependencies to older/newer major versions than what's resolvable; npm 7+ strict peer resolution vs packages built for npm 6; mixed versions of claude plugin deps.

Related errors

AI-assisted analysis of thedotmack/claude-mem@d8bc9755e7 (2026-09-17). Data as JSON: /api/errors/870a6638f2f1f77d. Report an issue: GitHub.

Appendix: source

Thrown at src/npx-cli/commands/install.ts:809

      component: 'marketplace-npm-install',
      phase: 'marketplace-deps',
      cause: new Error('npm install timed out'),
      details: strictResult.stderr.slice(0, 4000),
    }, summary);
  }

  if (!isEresolve(strictResult.stderr)) {
    // A strict failure with no ERESOLVE is a real bug — never retry, ABORT.
    installerError(ErrorSeverity.ABORT, {
      component: 'marketplace-npm-install',
      phase: 'marketplace-deps',
      cause: new Error(`npm install failed (exit ${strictResult.code})`),
      details: strictResult.stderr.slice(0, 4000),
    }, summary);
  }

  // Confirmed ERESOLVE — log loudly, attempt one fallback with --legacy-peer-deps.
  log.warn('npm reported an ERESOLVE peer-dependency conflict in marketplace deps; retrying once with --legacy-peer-deps.');
  log.warn(extractEresolveBlock(strictResult.stderr));

  const legacyResult = await runNpmStrict(marketplaceDir, [...baseFlags, '--legacy-peer-deps']);
  if (legacyResult.code === 0) {
    summary.warnings.push({
      component: 'marketplace-npm-install',
      message: 'tree-sitter peer-dep ERESOLVE was resolved with the --legacy-peer-deps fallback. Benign for the marketplace install; re-evaluate when tree-sitter peer ranges change.',
      remediation: 'No action required.',
    });
    return;
  }

  installerError(ErrorSeverity.ABORT, {
    component: 'marketplace-npm-install',
    phase: 'marketplace-deps',
    cause: new Error(`npm install --legacy-peer-deps still failed (exit ${legacyResult.code}): ERESOLVE`),
    details: legacyResult.stderr.slice(0, 4000),
  }, summary);

View on GitHub (pinned to d8bc9755e7)