BerriAI/litellm · error · ValueError

Invalid AWS region format: {aws_region_name!r}. Region names

Error message

Invalid AWS region format: {aws_region_name!r}. Region names must contain only lowercase letters, digits, and hyphens.

What it means

Error "Invalid AWS region format: {aws_region_name!r}. Region names must contain only lowercase letters, digits, and hyphens." thrown in BerriAI/litellm.

Source

Thrown at litellm/llms/bedrock/base_aws_llm.py:611

                    aws_region_name = configured_region
                else:
                    aws_region_name = "us-west-2"
            except Exception:
                aws_region_name = "us-west-2"

        self._validate_aws_region_name(aws_region_name)
        return aws_region_name

    @staticmethod
    def _validate_aws_region_name(aws_region_name: str | None) -> None:
        """
        Validate that an AWS region name conforms to the expected format
        (lowercase alphanumerics and hyphens). Raises ValueError otherwise.
        """
        if aws_region_name is None:
            return
        if not isinstance(aws_region_name, str) or not _VALID_AWS_REGION_PATTERN.match(aws_region_name):
            raise ValueError(
                f"Invalid AWS region format: {aws_region_name!r}. "
                "Region names must contain only lowercase letters, digits, and hyphens."
            )

    @staticmethod
    def _parse_sts_region_from_endpoint(
        aws_sts_endpoint: str | None,
    ) -> str | None:
        """Extract region from sts.{region}.amazonaws.com or vpce-x.sts.{region}.vpce.amazonaws.com."""
        if not aws_sts_endpoint:
            return None
        host: Final = urllib.parse.urlparse(aws_sts_endpoint).hostname or ""
        match: Final = _STS_REGION_FROM_ENDPOINT_PATTERN.search(host)
        return match.group(1) if match else None

    @staticmethod
    def _resolve_sts_region(aws_sts_endpoint: str | None = None) -> str | None:
        """STS signing region: parsed from aws_sts_endpoint else AWS_REGION / AWS_DEFAULT_REGION."""

View on GitHub (pinned to 6c2dcb801b)

Solutions

1. Use a valid AWS region name (lowercase letters, digits, hyphens), e.g. 'us-east-1'.

When it happens

Trigger: Thrown at litellm/llms/bedrock/base_aws_llm.py:611 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of BerriAI/litellm@6c2dcb801b (2026-08-15). Data as JSON: /api/errors/59eb24f9e593dc2a. Report an issue: GitHub.