crewAIInc/crewAI · error · BedrockValidationError

session_id must be a string

Error message

session_id must be a string

What it means

A BedrockValidationError raised when an optional session_id is provided but is not a string. session_id is optional (the check is `if self.session_id and not isinstance(...)`), so the error only fires when a truthy non-string value is supplied.

Source

Thrown at lib/crewai-tools/src/crewai_tools/aws/bedrock/agents/invoke_agent_tool.py:87

            self.description = description

        self._validate_parameters()

    def _validate_parameters(self) -> None:
        """Validate the parameters according to AWS API requirements."""
        try:
            if not self.agent_id:
                raise BedrockValidationError("agent_id cannot be empty")
            if not isinstance(self.agent_id, str):
                raise BedrockValidationError("agent_id must be a string")

            if not self.agent_alias_id:
                raise BedrockValidationError("agent_alias_id cannot be empty")
            if not isinstance(self.agent_alias_id, str):
                raise BedrockValidationError("agent_alias_id must be a string")

            if self.session_id and not isinstance(self.session_id, str):
                raise BedrockValidationError("session_id must be a string")

        except BedrockValidationError as e:
            raise BedrockValidationError(f"Parameter validation failed: {e!s}") from e

    def _run(self, query: str) -> str:
        try:
            import boto3
            from botocore.exceptions import ClientError
        except ImportError as e:
            raise ImportError(
                "`boto3` package not found, please run `uv add boto3`"
            ) from e

        try:
            # Initialize the Bedrock Agent Runtime client
            bedrock_agent = boto3.client(
                "bedrock-agent-runtime",
                region_name=os.getenv(

View on GitHub (pinned to 754d7323be)

Solutions

1. Convert: `session_id=str(uuid.uuid4())`.
2. If reusing an AWS-returned sessionId from a previous InvokeAgent response, take the raw string field.
3. Omit session_id entirely if you do not need cross-invocation memory.

Example fix

# before
tool = BedrockAgentTools(agent_id="ABCD123456", agent_alias_id="TSTALIASID", session_id=uuid.uuid4())

# after
tool = BedrockAgentTools(agent_id="ABCD123456", agent_alias_id="TSTALIASID", session_id=str(uuid.uuid4()))

if session_id is not None and not isinstance(session_id, str):
    session_id = str(session_id)

def is_session_id(v) -> bool:
    return v is None or isinstance(v, str)

try:
    tool = BedrockAgentTools(agent_id=aid, agent_alias_id=alias, session_id=sid)
except BedrockValidationError as e:
    if "session_id must be a string" in str(e):
        tool = BedrockAgentTools(agent_id=aid, agent_alias_id=alias, session_id=str(sid))
    else:
        raise

When it happens

Trigger: Constructing the tool with session_id as an int/UUID object/list — e.g. `session_id=uuid.uuid4()` (UUID object, not str) or a numeric session key from a database.

Common situations: Generating session IDs with uuid.uuid4() and forgetting str(); passing a pandas/numpy integer session key; reusing an internal session object instead of its string identifier.

Related errors

• agent_id must be a string
• agent_alias_id must be a string
• knowledge_base_id must be a string
• number_of_results must be an integer
• agent_id cannot be empty

AI-assisted analysis of crewAIInc/crewAI@754d7323be (2026-08-15). Data as JSON: /api/errors/092319b11c18df94. Report an issue: GitHub.