What causes "Invalid S3 client parameters for get_bucket_location: {e}" in remotion-dev/remotion?

Inspect the wrapped exception `e` (via __cause__) for the exact ParamValidationError field.

remotion-dev/remotion · error · RemotionInvalidArgumentException

Invalid S3 client parameters for get_bucket_location: {e}

Error message

Invalid S3 client parameters for get_bucket_location: {e}

What it means

Raised when boto3 rejects the parameters to get_bucket_location with a ParamValidationError (before any network call). The original ClientError is NOT caught here - it is re-raised; this wrapper only handles malformed parameter shapes passed to the S3 client.

Source

Thrown at packages/lambda-python/remotion_lambda/remotionclient.py:321

        """
        try:
            # Type hint for the response from get_bucket_location
            bucket_region_response: Dict[str, Any] = s3_client.get_bucket_location(Bucket=bucket_name)
            location: Optional[str] = bucket_region_response.get('LocationConstraint')

            # us-east-1 returns None for LocationConstraint
            return location == self.region or (
                location is None and self.region == REGION_US_EAST
            )
        except ClientError as e:
            logger.debug(
                "Could not get bucket location for %s (possibly permission issue): %s",
                bucket_name,
                e,
            )
            raise e
        except ParamValidationError as e:
            raise RemotionInvalidArgumentException(
                f"Invalid S3 client parameters for get_bucket_location: {e}"
            ) from e

    def _get_or_create_bucket(self) -> str:
        """Get existing bucket or create a new one following JS SDK logic."""
        buckets = self._get_remotion_buckets()

        if len(buckets) > 1:
            raise RemotionException(
                f"You have multiple buckets ({', '.join(buckets)}) in your S3 region "
                f"({self.region}) starting with \"remotionlambda-\". "
                "Please see https://remotion.dev/docs/lambda/multiple-buckets."
            )

        if len(buckets) == 1:
            return buckets[0]

        bucket_name = self._make_bucket_name()

View on GitHub (pinned to 78fe4bb3fd)

Solutions

Inspect the wrapped exception `e` (via __cause__) for the exact ParamValidationError field.
Confirm the resolved bucket name is a non-empty string before calling render APIs.
Validate that the configured region produces a valid S3 endpoint (e.g. 'us-east-1', not '').
If you control the session, ensure the boto3 Session was created with a valid region_name.

Example fix

// before
client = RemotionClient(region='', serve_url=..., function_name=...)
client.renderMedia(...)

# after
client = RemotionClient(region='us-east-1', serve_url=..., function_name=...)
client.renderMedia(...)

Defensive patterns

Strategy: try-catch

Validate before calling

def preflight_s3(session, bucket_name: str, region: str) -> None:
    if not isinstance(bucket_name, str) or not bucket_name.strip():
        raise ValueError(f'invalid bucket_name: {bucket_name!r}')
    if not re.match(r'^[a-z0-9][a-z0-9.-]*[a-z0-9]$', bucket_name) or len(bucket_name) > 63:
        raise ValueError(f'bucket_name not S3-compliant: {bucket_name!r}')

Type guard

def is_valid_bucket_name(value) -> bool:\n    return (isinstance(value, str)\n            and 3 <= len(value) <= 63\n            and bool(re.match(r'^[a-z0-9][a-z0-9.-]*[a-z0-9]$', value)))

Try / catch

try:\n    client.render_media(...)\nexcept RemotionInvalidArgumentException as e:\n    cause = e.__cause__\n    log.error('S3 param validation failed: %s', cause)\n    raise

Prevention

Validate bucket names match S3 naming rules before relying on them.
Use a valid boto3 Session with a proper region_name.
In tests, stub boto3 with the exact parameter shapes boto3 expects.

When it happens

Trigger: Calling _verify_bucket_region (used internally during _get_or_create_bucket) when bucket_name is None, empty, or not a string; when the S3 client itself was constructed with bad parameters; integration test stubs that feed non-string bucket names.

Common situations: Internal corruption of the bucket name (e.g. a bucket lookup returned an empty string); a malformed region propagating into the S3 client endpoint; mocking the S3 client incorrectly in tests; bucket name resolution returning a non-scalar value.

Related errors

AI-assisted analysis of remotion-dev/remotion@78fe4bb3fd (2026-08-12). Data as JSON: /api/errors/2cebbeab1b47c863. Report an issue: GitHub.