BerriAI/litellm · error · Exception

param `{key}` is not supported on Bytez

Error message

param `{key}` is not supported on Bytez

What it means

The Bytez chat transformation maps OpenAI parameter names to Bytez equivalents via openai_to_bytez_param_map. Parameters explicitly mapped to False are known-unsupported; passing any of them raises this bare Exception unless drop_params is set, in which case they are silently skipped. Params mapped to None pass through unchanged; params with an alias are renamed.

Source

Thrown at litellm/llms/bytez/chat/transformation.py:106

    def map_openai_params(
        self,
        non_default_params: dict,
        optional_params: dict,
        model: str,
        drop_params: bool,
    ) -> dict:
        adapted_params: Final = {}

        all_params: Final = {**non_default_params, **optional_params}

        for key, value in all_params.items():
            alias = self.openai_to_bytez_param_map.get(key)

            if alias is False:
                if drop_params:
                    continue

                raise Exception(f"param `{key}` is not supported on Bytez")

            if alias is None:
                adapted_params[key] = value
                continue

            adapted_params[alias] = value

        return adapted_params

    def validate_environment(
        self,
        headers: dict,
        model: str,
        messages: list[AllMessageValues],
        optional_params: dict,
        litellm_params: dict,
        api_key: str | None = None,
        api_base: str | None = None,

View on GitHub (pinned to 6c2dcb801b)

Solutions

1. Pass drop_params=True (or set litellm.drop_params) so unsupported params are dropped instead of raising.
2. Remove the offending param named in the message for Bytez calls.
3. Branch your request builder per provider so only mapped params reach Bytez.

Example fix

# before
litellm.completion(model="bytez/meta-llama/Llama-3-8b", messages=m, logit_bias={"1": -100})

# after
litellm.completion(model="bytez/meta-llama/Llama-3-8b", messages=m, drop_params=True)

BYTEZ_SAFE_PARAMS = {"temperature", "max_tokens", "top_p", "stream"}  # subset known to pass through
bytez_params = {k: v for k, v in kwargs.items() if k in BYTEZ_SAFE_PARAMS}

try:
    litellm.completion(model="bytez/...", messages=m, **kwargs)
except Exception as e:
    if "not supported on Bytez" in str(e):
        litellm.completion(model="bytez/...", messages=m, drop_params=True, **kwargs)
    else:
        raise

When it happens

Trigger: Calling a bytez/ chat completion with a parameter the map marks False (e.g. certain OpenAI-only params) while drop_params is not enabled — for example forwarding a generic kwargs dict containing that param to litellm.completion(model="bytez/...").

Common situations: Provider-agnostic wrapper code that sends the same optional params (logit_bias, user, function-style args, etc.) to every provider; switching an OpenAI-targeted call to a Bytez model without pruning params.

Related errors

• Parameter {k} is not supported for model {model}. Supported
• Parameter {k} is not supported for model {model}. Supported
• Error transforming text to image params: {e}. Got params: {t
• kwarg `messages` must be an array of messages that follow th
• Prop `type` is not a string

AI-assisted analysis of BerriAI/litellm@6c2dcb801b (2026-08-15). Data as JSON: /api/errors/e858d81cf62325d3. Report an issue: GitHub.