BerriAI/litellm · error · HTTPException

Unsolicited (IdP-initiated) SAML responses are disabled.

Error message

Unsolicited (IdP-initiated) SAML responses are disabled.

What it means

An IdP-initiated (unsolicited) response arrived — no InResponseTo — while SAML_ALLOW_UNSOLICITED is not enabled, so the login is refused with 401. At-fault condition is the deployment's unsolicited-response policy versus the IdP's behavior.

Source

Thrown at litellm/proxy/management_endpoints/sso/saml_sso.py:385

        if in_response_to is not None:
            authn_key: Final = f"{_SAML_AUTHN_REQUEST_CACHE_PREFIX}:{in_response_to}"
            if cache.get_cache(key=authn_key) is None:
                raise HTTPException(
                    status_code=status.HTTP_401_UNAUTHORIZED,
                    detail="SAML response references an unknown or already-used login request.",
                )
            if browser_request_id is None or not secrets.compare_digest(browser_request_id, in_response_to):
                raise HTTPException(
                    status_code=status.HTTP_401_UNAUTHORIZED,
                    detail="SAML response is not bound to this browser's login request.",
                )
        elif browser_request_id is not None:
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="SAML response is not bound to this browser's login request.",
            )
        elif not SAMLAuthHandler._bool_env("SAML_ALLOW_UNSOLICITED", False):
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="Unsolicited (IdP-initiated) SAML responses are disabled.",
            )
        elif cache.redis_cache is None:
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail=(
                    "Unsolicited (IdP-initiated) SAML responses require a shared Redis cache "
                    "so the replay guard is enforced across every worker."
                ),
            )

        assertion_id: Final = cast(str | None, auth.get_last_assertion_id())  # cast-ok: untyped python3-saml
        if assertion_id is None:
            raise HTTPException(
                status_code=status.HTTP_401_UNAUTHORIZED,
                detail="SAML assertion is missing the required ID attribute.",
            )

View on GitHub (pinned to 77b7c6c40c)

Solutions

1. Initiate login from the SP (proxy login page) instead of the IdP, or enable IdP-initiated SSO explicitly.

When it happens

Trigger: Thrown at litellm/proxy/management_endpoints/sso/saml_sso.py:385 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of BerriAI/litellm@77b7c6c40c (2026-08-18). Data as JSON: /api/errors/cdfb588a0b694cc0. Report an issue: GitHub.