BerriAI/litellm · critical · BedrockError

Bedrock event-stream shape could not be loaded from botocore

Error message

Bedrock event-stream shape could not be loaded from botocore. Ensure botocore is correctly installed.

What it means

Identical condition to the decoder variant in invoke_handler.py, raised from the shared base event-stream decoder in common_utils.py: get_bedrock_response_stream_shape() returned None, so litellm could not obtain the bedrock-runtime 'responseStream' shape from the installed botocore and cannot decode the AWS binary event-stream. Surface as BedrockError 500 with the fixed botocore-installation message.

Source

Thrown at litellm/llms/bedrock/common_utils.py:1288

                status_code = int(modeled_status)

    return BedrockError(status_code=status_code, message=message)


class BedrockEventStreamDecoderBase:
    """
    Base class for event stream decoding for Bedrock
    """

    def __init__(self):
        from botocore.parsers import EventStreamJSONParser

        self.parser = EventStreamJSONParser()

    def _parse_message_from_event(self, event) -> str | None:
        response_stream_shape: Final = get_bedrock_response_stream_shape()
        if response_stream_shape is None:
            raise BedrockError(
                status_code=500,
                message=(
                    "Bedrock event-stream shape could not be loaded from botocore. "
                    "Ensure botocore is correctly installed."
                ),
            )
        response_dict: Final = event.to_response_dict()
        parsed_response: Final = self.parser.parse(response_dict, response_stream_shape)

        if response_dict["status_code"] != 200:
            raise build_bedrock_stream_error(response_dict, response_stream_shape)
        if "chunk" in parsed_response:
            chunk = parsed_response.get("chunk")
            if not chunk:
                return None
            return chunk.get("bytes").decode()
        else:
            chunk = response_dict.get("body")

View on GitHub (pinned to 6c2dcb801b)

Solutions

1. Install/upgrade a full botocore: pip install -U boto3 botocore.
2. Verify the service model exists: inspect botocore.loaders for bedrock-runtime service-2.json in the installed package.
3. If you must pin botocore, use a version that ships bedrock-runtime event-stream models (recent 1.3x+).
4. Repair corrupted installs with pip install --force-reinstall botocore.

Example fix

# before (image installs botocore-core without service models)
pip install botocore-core

# after
pip install -U boto3 botocore
python -c "from litellm.llms.bedrock.common_utils import get_bedrock_response_stream_shape; print(get_bedrock_response_stream_shape())"  # must not be None

from litellm.llms.bedrock.common_utils import get_bedrock_response_stream_shape
if get_bedrock_response_stream_shape() is None:
    raise RuntimeError("botocore lacks bedrock-runtime event-stream model - run: pip install -U boto3 botocore")

def event_stream_shape_available() -> bool:
    try:
        from litellm.llms.bedrock.common_utils import get_bedrock_response_stream_shape
        return get_bedrock_response_stream_shape() is not None
    except Exception:
        return False

from litellm.exceptions import BedrockError
try:
    for chunk in litellm.completion(model="bedrock/<model>", messages=msgs, stream=True):
        pass
except BedrockError as e:
    if "event-stream shape" in str(e):
        raise RuntimeError("Dependency fix required: pip install -U boto3 botocore") from e
    raise

When it happens

Trigger: Any Bedrock streaming decode that goes through the base decoder when botocore is absent, incomplete (missing bedrock-runtime service model), or too old to contain the event-stream shape litellm looks up.

Common situations: Docker images stripping botocore service models, dependency downgrades in lockfiles, lambda layers with partial boto3 installs, or freshly added model families hitting this code path before botocore is upgraded.

Related errors

• Bedrock event-stream shape could not be loaded from botocore
• Received streaming error - {e}
• Model needs to be set for bedrock
• Missing boto3 to call bedrock. Run 'pip install boto3'.
• Missing boto3 to call S3. Run 'pip install boto3'.

AI-assisted analysis of BerriAI/litellm@6c2dcb801b (2026-08-15). Data as JSON: /api/errors/a550dda2addc1dd6. Report an issue: GitHub.