BerriAI/litellm · warning · ValueError

Unsupported HTTP method: {method}

Error message

Unsupported HTTP method: {method}

What it means

sign_with_oci_signer whitelists HTTP methods {POST, GET, PUT, DELETE, PATCH} before building the OCIRequestWrapper; anything else in optional_params['method'] (after str().upper()) — e.g. 'HEAD', 'OPTIONS', a typo, or a non-method string — raises ValueError because the OCI signing scheme is only implemented for those verbs.

Source

Thrown at litellm/llms/oci/common_utils.py:218

# ---------------------------------------------------------------------------
# Signing implementations (shared by chat, embed, and rerank configs)
# ---------------------------------------------------------------------------


def sign_with_oci_signer(
    headers: dict,
    optional_params: dict,
    request_data: dict,
    api_base: str,
) -> tuple[dict, bytes]:
    """Sign a request using an OCI SDK Signer object passed in optional_params."""
    oci_signer: Final = optional_params.get("oci_signer")
    body: Final = json.dumps(request_data).encode("utf-8")
    method: Final = str(optional_params.get("method", "POST")).upper()

    if method not in {"POST", "GET", "PUT", "DELETE", "PATCH"}:
        raise ValueError(f"Unsupported HTTP method: {method}")

    prepared_headers: Final = {**headers}
    prepared_headers.setdefault("content-type", "application/json")
    prepared_headers.setdefault("content-length", str(len(body)))

    request_wrapper: Final = OCIRequestWrapper(method=method, url=api_base, headers=prepared_headers, body=body)

    if oci_signer is None:
        raise ValueError("oci_signer cannot be None when calling sign_with_oci_signer")

    try:
        oci_signer.do_request_sign(request_wrapper, enforce_content_headers=True)
    except Exception as e:
        raise OCIError(
            status_code=500,
            message=(
                f"Failed to sign request with provided oci_signer: {e}. "
                "The signer must implement the OCI SDK Signer interface with a "

View on GitHub (pinned to 6c2dcb801b)

Solutions

1. Use one of the supported verbs; for chat/embeddings the default POST is correct — simply omit 'method'.
2. If a foreign 'method' key leaks into optional_params from your stack, strip it before calling litellm.
3. For health checks, hit the endpoint with an unsigned GET or use the OCI SDK instead of forcing HEAD through signing.

Example fix

# before
optional_params["method"] = "HEAD"  # ValueError

# after
optional_params.pop("method", None)  # default POST

method = str(optional_params.get("method", "POST")).upper()
assert method in {"POST", "GET", "PUT", "DELETE", "PATCH"}, f"unsupported method {method}"

from typing import Any

def is_supported_oci_method(m: Any) -> bool:
    return isinstance(m, str) and m.upper() in {"POST", "GET", "PUT", "DELETE", "PATCH"}

try:
    sign_with_oci_signer(headers, optional_params, data, url)
except ValueError as e:
    if "Unsupported HTTP method" in str(e):
        optional_params.pop("method", None)  # fall back to default POST
    raise

When it happens

Trigger: Passing optional_params={'method': 'head'} or 'options' when calling the OCI signing helper directly; a framework injecting its own 'method' key into optional_params (e.g. a generic HTTP layer reusing the dict); misspellings like 'pos'.

Common situations: Integrations that forward their transport's method into optional_params; code copied from another provider expecting lowercase verbs (handled) but then extending to unsupported verbs; generic retry layers attempting HEAD health checks through the signing path.

Related errors

• Invalid OCI region {region!r}: must match ^[a-z][a-z0-9-]{{0
• Failed to sign request with provided oci_signer: {e}. The si
• Private key is required for OCI authentication. Provide eith
• oci_compartment_id is required for OCI embedding requests. P
• Invalid mode: {custom_auth_settings['mode']}

AI-assisted analysis of BerriAI/litellm@6c2dcb801b (2026-08-15). Data as JSON: /api/errors/ce6ddc9ae25ed47f. Report an issue: GitHub.