pathwaycom/pathway · error · ValueError

Unexpected argument for {format!r} format: {param}

Error message

Unexpected argument for {format!r} format: {param}

What it means

Error "Unexpected argument for {format!r} format: {param}" thrown in pathwaycom/pathway.

Source

Thrown at python/pathway/io/_utils.py:309

    csv_settings: CsvParserSettings | None = None,
    json_field_paths: dict[str, str] | None = None,
    schema_registry_settings: SchemaRegistrySettings | None = None,
    with_native_record_key: bool = False,
    _stacklevel: int = 1,
) -> tuple[type[Schema], api.DataFormat]:
    data_format_type = get_data_format_type(format, SUPPORTED_INPUT_FORMATS)

    if data_format_type == "identity":
        kwargs = locals()
        unexpected_params = [
            "schema",
            "csv_settings",
            "json_field_paths",
            "schema_registry_settings",
        ]
        for param in unexpected_params:
            if param in kwargs and kwargs[param] is not None:
                raise ValueError(f"Unexpected argument for {format!r} format: {param}")

        parse_utf8 = format not in ("binary", "only_metadata", "raw")
        schema = construct_raw_data_schema_by_flags(
            with_native_record_key=with_native_record_key,
            parse_utf8=parse_utf8,
            with_metadata=with_metadata,
        )
        schema, api_schema = read_schema(schema)

        return schema, api.DataFormat(
            format_type=data_format_type,
            **api_schema,
            parse_utf8=parse_utf8,
            key_generation_policy=(
                api.KeyGenerationPolicy.ALWAYS_AUTOGENERATE
                if autogenerate_key
                else api.KeyGenerationPolicy.PREFER_MESSAGE_KEY
            ),

View on GitHub (pinned to fa2f74a464)

Solutions

1. Remove the parameter that does not apply to the selected format, or switch to a format that accepts it.

Example fix

pw.io.fs.read(path, format='json', schema=MySchema)  # no csv-only params

When it happens

Trigger: Thrown at python/pathway/io/_utils.py:309 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of pathwaycom/pathway@fa2f74a464 (2026-08-15). Data as JSON: /api/errors/7ef65a94a7db8314. Report an issue: GitHub.