vercel/ai · error

ACP runtime environment key ${JSON.stringify(key)} cannot be

Error message

ACP runtime environment key ${JSON.stringify(key)} cannot be configured in both forwardEnv and credentialEnv.

What it means

A key listed in both forwardEnv (forwarded host env vars) and credentialEnv (securely handled credential vars) is ambiguous — the runtime cannot forward and credential-treat the same variable. createACPV1 rejects such overlap to keep environment handling deterministic. Keys are compared as an exact set intersection.

Source

Thrown at packages/harness-acp/src/v1/implementation.ts:86

  } else if (source.type === 'npm-simple') {
    validateNpmSimpleSource({ source });
  } else if (source.command.trim().length === 0) {
    throw new Error('ACP source.command must not be empty.');
  }
  if (!EXECUTABLE_NAME_REGEXP.test(implementation.executable)) {
    throw new Error(
      `ACP executable must be a bare command name without a path; received ${JSON.stringify(implementation.executable)}.`,
    );
  }

  validateForwardEnvironment({ forwardEnv: implementation.forwardEnv });
  validateForwardEnvironment({ forwardEnv: implementation.credentialEnv });
  validateEnvironment({ env: implementation.env });
  const forwardedKeys = new Set(implementation.forwardEnv ?? []);
  const credentialKeys = new Set(implementation.credentialEnv ?? []);
  for (const key of credentialKeys) {
    if (forwardedKeys.has(key)) {
      throw new Error(
        `ACP runtime environment key ${JSON.stringify(key)} cannot be configured in both forwardEnv and credentialEnv.`,
      );
    }
  }
  for (const key of Object.keys(implementation.env ?? {})) {
    if (forwardedKeys.has(key)) {
      throw new Error(
        `ACP runtime environment key ${JSON.stringify(key)} cannot be configured in both forwardEnv and env.`,
      );
    }
    if (credentialKeys.has(key)) {
      throw new Error(
        `ACP runtime environment key ${JSON.stringify(key)} cannot be configured in both credentialEnv and env.`,
      );
    }
  }
}

View on GitHub (pinned to 69428b1f8b)

Solutions

1. Remove the duplicated key from one of the two arrays — keep it in credentialEnv if it is a secret, otherwise forwardEnv.
2. Audit both arrays with an intersection check before constructing the settings.
3. If the var needs both behaviors, rename or split it (e.g. use a distinct credential var).

Example fix

// before
createACPV1({ forwardEnv: ['ANTHROPIC_API_KEY'], credentialEnv: ['ANTHROPIC_API_KEY'] });
// after
createACPV1({ credentialEnv: ['ANTHROPIC_API_KEY'] });

const forwarded = new Set(implementation.forwardEnv ?? []);
const dup = (implementation.credentialEnv ?? []).filter(k => forwarded.has(k));
if (dup.length > 0) throw new Error(`Keys in both forwardEnv and credentialEnv: ${dup.join(', ')}`);

function envListsAreDisjoint(a, b) {
  const setB = new Set(b ?? []);
  return !(a ?? []).some(k => setB.has(k));
}

try {
  const impl = createACPV1(settings);
} catch (err) {
  if (err instanceof Error && err.message.includes('both forwardEnv and credentialEnv')) {
    console.error('Remove the duplicated key from one list');
  }
  throw err;
}

When it happens

Trigger: createACPV1 where any string appears in both implementation.forwardEnv and implementation.credentialEnv, e.g. forwardEnv: ['API_KEY'], credentialEnv: ['API_KEY'].

Common situations: Incrementally adding env vars to both lists while debugging auth, copy-pasting lists between forwardEnv and credentialEnv, or merging two config files that each list the same var.

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 runtime environment key ${JSON.stringify(key)} cannot be
• ACP runtime environment key ${JSON.stringify(key)} cannot be
• ACP environment variable name is invalid: ${JSON.stringify(k
• ACP runtime environment value for ${key} contains NUL.
• Invalid argument for parameter output: Invalid output type.

AI-assisted analysis of vercel/ai@69428b1f8b (2026-08-30). Data as JSON: /api/errors/fa3d7a55dc5c1f21. Report an issue: GitHub.