angular/angular-cli · error · Error

An unexpected error happened; could not determine version fo

Error message

An unexpected error happened; could not determine version for package ${name}.

What it means

Thrown by _buildPackageInfo when neither the locally installed package's package.json nor any other source could supply an installed version for the package being updated. The CLI needs the installed version to compute the update range but found nothing on disk or in the registry metadata.

Source

Thrown at packages/angular/cli/src/commands/update/update-resolver.ts:490

  const name = npmPackageJson.name;
  const packageJsonRange = allDependencies.get(name);
  if (!packageJsonRange) {
    throw new Error(`Package ${JSON.stringify(name)} was not found in package.json.`);
  }

  const localPkgJson = getInstalledPackageJson(name, workspaceRoot);
  let installedVersion = localPkgJson?.version;

  if (!installedVersion) {
    installedVersion = (await getSatisfyingVersion(
      registryClient,
      npmPackageJson,
      packageJsonRange,
    )) as VersionRange | undefined;
  }

  if (!installedVersion) {
    throw new Error(
      `An unexpected error happened; could not determine version for package ${name}.`,
    );
  }

  const installedPackageJson =
    localPkgJson || (await registryClient.getManifest(name, installedVersion));
  if (!installedPackageJson) {
    throw new Error(
      `An unexpected error happened; package ${name} has no version ${installedVersion}.`,
    );
  }

  let targetVersion: VersionRange | undefined = packages.get(name);
  if (targetVersion) {
    const distTags = npmPackageJson['dist-tags'] ?? {};
    let resolvedVersion: string | undefined =
      distTags[targetVersion] ?? (targetVersion === 'next' ? distTags['latest'] : undefined);

View on GitHub (pinned to bb72145f9a)

Solutions

1. Run your package manager's install command (npm install / yarn / pnpm install) to restore node_modules.
2. Verify node_modules/<pkg>/package.json exists and has a version field.
3. Delete node_modules and lockfile and reinstall if corrupted.
4. Ensure you run ng update from the workspace root.

Example fix

// before
ng update @angular/core  // node_modules missing
// after
npm install
ng update @angular/core

import { existsSync, readFileSync } from 'fs';
const manifest = `node_modules/${name}/package.json`;
if (!existsSync(manifest) || !JSON.parse(readFileSync(manifest,'utf8')).version) {
  throw new Error(`Run install first: ${name} is not installed`);
}

function isInstalled(name) {
  try {
    return typeof require(`${name}/package.json`).version === 'string';
  } catch { return false; }
}

try {
  await ngUpdate([name]);
} catch (e) {
  if (String(e.message).includes('could not determine version')) {
    execSync('npm install', { stdio: 'inherit' }); // restore node_modules, then retry
  }
}

When it happens

Trigger: The package is listed in package.json but not actually installed (missing node_modules); the installed package directory exists but its package.json is missing/corrupt so localPkgJson?.version is undefined; registry lookups also failed to yield a version.

Common situations: Fresh checkout without running npm install; interrupted install leaving broken node_modules; pnpm/yarn PnP layouts the CLI cannot read; corrupted node_modules after a failed upgrade.

Related errors

• Could not find the '${builderConf}' builder's node package.
• Package ${name} is not installed.
• An unexpected error happened; package ${name} has no version
• Package ${JSON.stringify(pkgName)} is not in package.json.
• Repository is not clean. Update changes will be mixed with p

AI-assisted analysis of angular/angular-cli@bb72145f9a (2026-08-30). Data as JSON: /api/errors/269cecb2887ded97. Report an issue: GitHub.