vercel/ai · error

ACP npm package name is invalid: ${JSON.stringify(source.pac

Error message

ACP npm package name is invalid: ${JSON.stringify(source.packageName)}.

What it means

For 'npm-simple' sources, source.packageName must match a valid npm package name: optional @scope/, lowercase alphanumerics, and only . _ - characters, no leading separators. createACPV1 validates it with PACKAGE_NAME_REGEXP and rejects anything else so the installer does not attempt a doomed npm fetch.

Source

Thrown at packages/harness-acp/src/v1/implementation.ts:319

  for (const name of implementation.credentialEnv ?? []) {
    const value = credentialEnv[name];
    if (value != null && value.length > 0) {
      forwardedEnvironment[name] = value;
    }
  }
  return {
    ...forwardedEnvironment,
    ...implementation.env,
  };
}

function validateNpmSimpleSource({
  source,
}: {
  source: ACPNpmSimpleSource;
}): void {
  if (!PACKAGE_NAME_REGEXP.test(source.packageName)) {
    throw new Error(
      `ACP npm package name is invalid: ${JSON.stringify(source.packageName)}.`,
    );
  }
  if (
    source.packageVersion != null &&
    !EXACT_SEMVER_REGEXP.test(source.packageVersion)
  ) {
    throw new Error(
      `ACP npm package version must be an exact semantic version; received ${JSON.stringify(source.packageVersion)}.`,
    );
  }
}

function validateEnvironment({
  env,
}: {
  env: Readonly<Record<string, string>> | undefined;
}): void {

View on GitHub (pinned to 69428b1f8b)

Solutions

1. Use the exact published npm name, lowercase, e.g. '@zed-industries/claude-code-acp' or 'claude-code-acp'.
2. Run `npm view <name>` to confirm the package exists and the spelling is right.
3. If you need a non-registry source (git/URL), that is not npm-simple — use the appropriate source type or a command source.

Example fix

// before
createACPV1({ source: { type: 'npm-simple', packageName: 'Claude-Code-ACP' } });
// after
createACPV1({ source: { type: 'npm-simple', packageName: 'claude-code-acp' } });

const PACKAGE_NAME_REGEXP = /^(?:@[a-z0-9][a-z0-9._-]*\/)?[a-z0-9][a-z0-9._-]*$/;
if (!PACKAGE_NAME_REGEXP.test(source.packageName)) {
  throw new Error(`Invalid npm package name: ${source.packageName}`);
}

function isValidNpmPackageName(name) {
  return typeof name === 'string' && /^(?:@[a-z0-9][a-z0-9._-]*\/)?[a-z0-9][a-z0-9._-]*$/.test(name);
}

try {
  const impl = createACPV1(settings);
} catch (err) {
  if (err instanceof Error && err.message.startsWith('ACP npm package name is invalid')) {
    console.error('Use the exact lowercase npm package name, including @scope/ if scoped');
  }
  throw err;
}

When it happens

Trigger: createACPV1 with source.type 'npm-simple' and packageName values like 'Claude ACP', '@scope', 'pkg!', 'UPPERCASE', or an empty string.

Common situations: Typo in the package name, using a display name instead of the npm name, wrong case (npm names are case-sensitive and must be lowercase), or trimming a git URL into the packageName field.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• ACP source.packageJson must not be empty.
• ACP source.pnpmWorkspaceYaml must not be empty.
• ACP npm package version must be an exact semantic version; r
• Invalid argument for parameter output: Invalid output type.
• Continuation maxAgeMs must be a positive integer.

AI-assisted analysis of vercel/ai@69428b1f8b (2026-08-30). Data as JSON: /api/errors/f77a05b33ee00e0f. Report an issue: GitHub.