BerriAI/litellm · error · ValueError

The response from {start_url} is missing required field(s):

Error message

The response from {start_url} is missing required field(s): {', '.join(missing_fields)}. The proxy version may not match this CLI; upgrade whichever is older.

What it means

Raised in the CLI SSO flow after a 2xx response when the parsed JSON object is missing one or more required fields of CliSsoStartData (e.g. the login/verification URLs). The missing field names are listed and the message suggests a version mismatch: the CLI is talking to an older/newer proxy whose /sso/cli/start contract differs; upgrade whichever side is older.

Source

Thrown at litellm/proxy/client/cli/commands/auth.py:457

        raise ValueError(
            f"Starting CLI login failed: HTTP {response.status_code} from {start_url}"
            + (f": {detail}" if detail else "")
        )

    try:
        data: Final[CliSsoStartData] = response.json()
    except ValueError:
        content_type: Final = response.headers.get("content-type", "unknown")
        raise ValueError(
            f"The proxy returned a non-JSON response from {start_url} (content-type: {content_type}). "
            "A proxy, load balancer, or auth gateway in front of LiteLLM may be intercepting the request. "
            f"Response starts with: {response.text[:200]!r}"
        )

    required_fields: Final[tuple[str, ...]] = ("login_id", "poll_secret", "user_code")
    missing_fields: Final = tuple(field for field in required_fields if not isinstance(data.get(field), str))
    if missing_fields:
        raise ValueError(
            f"The response from {start_url} is missing required field(s): {', '.join(missing_fields)}. "
            "The proxy version may not match this CLI; upgrade whichever is older."
        )
    return data


def _get_cli_sso_poll_headers(poll_secret: str) -> dict[str, str]:
    return {"x-litellm-cli-poll-secret": poll_secret}


def _poll_for_authentication(base_url: str, key_id: str, poll_secret: str) -> CliAuthResult | None:
    """
    Poll the server for authentication completion and handle team selection.

    Returns:
        Dictionary with authentication data if successful, None otherwise
    """
    poll_url: Final = f"{base_url}/sso/cli/poll/{key_id}"

View on GitHub (pinned to 77b7c6c40c)

Solutions

1. Upgrade whichever is older: the proxy or the CLI, so their login flows match.

Example fix

pip install -U litellm and upgrade the proxy deployment.

When it happens

Trigger: Thrown at litellm/proxy/client/cli/commands/auth.py:457 when the library encounters an invalid state.

Common situations: The proxy's login response lacked fields the CLI expects (version mismatch).

AI-assisted analysis of BerriAI/litellm@77b7c6c40c (2026-08-18). Data as JSON: /api/errors/37abf7c44a33285e. Report an issue: GitHub.