microsoft/graphrag · error · TypeError

list item is not [{item_type}]: {v} ({type(v)})

Error message

list item is not [{item_type}]: {v} ({type(v)})

What it means

After to_list confirms the value is a list, it optionally validates each element against item_type (e.g. str for text_unit_ids, float for embeddings). Any element of the wrong type raises TypeError naming the expected type and the offending value — commonly a list of floats where ints/strings appear, or mixed-type lists after parquet deserialization.

Source

Thrown at packages/graphrag/graphrag/query/input/loaders/utils.py:63

    value = _get_value(data, column_name, required=True)
    return None if value is None else str(value)


def to_list(
    data: Mapping[str, Any], column_name: str | None, item_type: type | None = None
) -> list:
    """Convert and validate a value to a list."""
    value = _get_value(data, column_name, required=True)
    if isinstance(value, np.ndarray):
        value = value.tolist()
    if not isinstance(value, list):
        msg = f"value is not a list: {value} ({type(value)})"
        raise TypeError(msg)
    if item_type is not None:
        for v in value:
            if not isinstance(v, item_type):
                msg = f"list item is not [{item_type}]: {v} ({type(v)})"
                raise TypeError(msg)
    return value


def to_optional_list(
    data: Mapping[str, Any], column_name: str | None, item_type: type | None = None
) -> list | None:
    """Convert and validate a value to an optional list."""
    if column_name is None or column_name not in data:
        return None
    value = data[column_name]
    if value is None:
        return None
    if isinstance(value, np.ndarray):
        value = value.tolist()
    if isinstance(value, str):
        value = [value]
    if not isinstance(value, list):
        msg = f"value is not a list: {value} ({type(value)})"

View on GitHub (pinned to f40e9a26ce)

Solutions

1. Inspect the failing element (message includes value and type) and fix upstream data quality
2. Coerce elements before validation: [str(x) for x in vals] or [float(x) for x in vals if x is not None]
3. Drop or rebuild rows with None/corrupted list entries, usually by re-running the indexing step

Example fix

# before
ids = to_list(row, 'text_unit_ids', item_type=str)  # contains ints
# after
row['text_unit_ids'] = [str(x) for x in row['text_unit_ids']]
ids = to_list(row, 'text_unit_ids', item_type=str)

vals = data.get(col, [])
if item_type is str:
    vals = [str(v) for v in vals]
elif item_type is float:
    vals = [float(v) for v in vals if v is not None]
data = {**data, col: vals}

def all_of_type(vals: list, t: type) -> bool:
    return all(isinstance(v, t) for v in vals)

try:
    vals = to_list(data, col, item_type=item_type)
except TypeError as e:
    bad = [v for v in data[col] if not isinstance(v, item_type)]
    logger.warning('bad items %r in %s', bad, col)
    vals = [v for v in data[col] if isinstance(v, item_type)]

When it happens

Trigger: to_list(data, 'text_unit_ids', item_type=str) where the parquet column holds mixed types (some None or numeric ids); embedding lists containing None because of failed embeds; communities data where children ids were read as ints.

Common situations: Parquet/pandas coercing id lists to mixed object dtype; partially failed embedding runs leaving None entries; artifacts from different GraphRAG versions using numeric vs string ids.

Related errors

• Column name is None
• value is not a list: {value} ({type(value)})
• request_id needs to be passed as a keyword argument
• k must be an integer > 0
• Invalid Role: {value}

AI-assisted analysis of microsoft/graphrag@f40e9a26ce (2026-08-27). Data as JSON: /api/errors/3569082b02223302. Report an issue: GitHub.