BerriAI/litellm · error · ValueError

Invalid value passed in for async_create_assistants. Only bo

Error message

Invalid value passed in for async_create_assistants. Only bool or None allowed

What it means

Raised by litellm.assistants.create_assistant when the 'async_create_assistants' kwarg is not a bool or None. Like the other assistants functions, this internal flag selects the sync vs async code path and is strictly type-checked via kwargs.pop before any API call is made.

Source

Thrown at litellm/assistants/main.py:250

    model: str,
    name: str | None = None,
    description: str | None = None,
    instructions: str | None = None,
    tools: list[dict[str, Any]] | None = None,
    tool_resources: dict[str, Any] | None = None,
    metadata: dict[str, str] | None = None,
    temperature: float | None = None,
    top_p: float | None = None,
    response_format: str | dict[str, str] | None = None,
    client: Any | None = None,
    api_key: str | None = None,
    api_base: str | None = None,
    api_version: str | None = None,
    **kwargs,
) -> Assistant | Coroutine[Any, Any, Assistant]:
    async_create_assistants: Final[bool | None] = kwargs.pop("async_create_assistants", None)
    if async_create_assistants is not None and not isinstance(async_create_assistants, bool):
        raise ValueError("Invalid value passed in for async_create_assistants. Only bool or None allowed")
    optional_params: Final = GenericLiteLLMParams(api_key=api_key, api_base=api_base, api_version=api_version, **kwargs)
    litellm_params_dict: Final = get_litellm_params(**kwargs)

    ### TIMEOUT LOGIC ###
    timeout = optional_params.timeout or kwargs.get("request_timeout", 600) or 600
    # set timeout for 10 minutes by default

    if (
        timeout is not None
        and isinstance(timeout, httpx.Timeout)
        and supports_httpx_timeout(custom_llm_provider) is False
    ):
        read_timeout: Final = timeout.read or 600
        timeout = read_timeout  # default 10 min timeout
    elif timeout is not None and not isinstance(timeout, httpx.Timeout):
        timeout = float(timeout)
    elif timeout is None:
        timeout = 600.0

View on GitHub (pinned to 6c2dcb801b)

Solutions

1. Omit the kwarg entirely, or pass a literal bool: async_create_assistants=True.
2. Prefer calling litellm.acreate_assistant(...) for async usage instead of the internal flag.
3. Coerce config-sourced flags with a helper like value in (True, 'true', '1', 1).

Example fix

# before
litellm.create_assistant(model="gpt-4o", name="bot", async_create_assistants="true")

# after
await litellm.acreate_assistant(model="gpt-4o", name="bot")
# or: litellm.create_assistant(model="gpt-4o", name="bot", async_create_assistants=True)

if "async_create_assistants" in kwargs and not isinstance(kwargs["async_create_assistants"], (bool, type(None))):
    kwargs["async_create_assistants"] = parse_bool(kwargs["async_create_assistants"])  # or pop it

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

When it happens

Trigger: Calling litellm.create_assistant(...) with async_create_assistants set to a string, int, or other non-bool value (e.g. async_create_assistants=1 or 'yes'). Any of these fails isinstance(x, bool).

Common situations: Flags sourced from argparse/env vars arriving as strings; autogenerated client code that treats every option as a string; confusion between this internal flag and the public acreate_assistants async function.

Related errors

• Invalid value passed in for aget_assistants. Only bool or No
• Invalid value passed in for async_delete_assistants. Only bo
• 'models' must be a string or list of strings
• 'models' param not in kwargs
• input must be a string or a list

AI-assisted analysis of BerriAI/litellm@6c2dcb801b (2026-08-15). Data as JSON: /api/errors/16808c80ac2a6e95. Report an issue: GitHub.