What causes "Failed to convert dictionary of lists to list of records" in OpenBB-finance/OpenBB?

Verify all value lists have equal length: assert len({len(v) for v in content.values()}) == 1.

OpenBB-finance/OpenBB · error · ValueError

Failed to convert dictionary of lists to list of records

Error message

Failed to convert dictionary of lists to list of records

What it means

Thrown by the OmniWidgetResponseModel model_validator when content is a dict whose values are all lists (the column->list table shape) but building a DataFrame from it and serializing to records fails. This is the dict-of-lists table conversion path; failures are chained into this ValueError.

Source

Thrown at openbb_platform/extensions/platform_api/openbb_platform_api/response_models.py:262

            isinstance(item, dict) for item in content
        ):
            values.parse_as = "table"
        elif isinstance(content, pd.DataFrame):
            values.parse_as = "table"
            try:
                content = json.loads(content.to_json(orient="records"))
            except Exception as e:
                raise ValueError("Failed to convert DataFrame to JSON") from e
            values.content = content
        elif isinstance(content, dict) and all(
            isinstance(v, list) for v in content.values()
        ):
            values.parse_as = "table"
            try:
                df = pd.DataFrame(content)
                content = json.loads(df.to_json(orient="records"))
            except Exception as e:
                raise ValueError(
                    "Failed to convert dictionary of lists to list of records"
                ) from e
            values.content = content
        elif isinstance(content, str) and content.strip():  # pylint: disable=R0916
            try:
                content = json.loads(content)
            except json.JSONDecodeError:
                # Remove trailing commas in objects and arrays
                try:
                    cleaned_content = re.sub(r",(\s*[}\]])", r"\1", content)
                    content = json.loads(cleaned_content)
                except json.JSONDecodeError:
                    pass

            values.parse_as = "table" if isinstance(content, (list, dict)) else "text"
            values.content = content
        else:
            values.parse_as = "text"

View on GitHub (pinned to 3e071fcc2c)

Solutions

Verify all value lists have equal length: assert len({len(v) for v in content.values()}) == 1.
Coerce non-serializable elements to primitives (str/float/int) before constructing the model.
Build the records list yourself (list(zip(...)) -> list of dicts) and pass it as content so the list-of-dicts branch is used.
Check e.__cause__ for the exact pandas error (usually 'All arrays must be of the same length').

Example fix

# before
content = {"a": [1, 2], "b": [3]}  # ragged
resp = OmniWidgetResponseModel(content=content)

# after
content = {"a": [1, 2], "b": [3, 4]}
resp = OmniWidgetResponseModel(content=content)

Defensive patterns

Strategy: validation

Validate before calling

lengths = {len(v) for v in content.values() if isinstance(v, list)}
assert len(lengths) <= 1, f"ragged columns: {lengths}"
records = [dict(zip(content, row)) for row in zip(*content.values())]
resp = OmniWidgetResponseModel(content=records)

Type guard

def is_wellformed_dict_of_lists(d) -> bool:
    return isinstance(d, dict) and bool(d) and all(
        isinstance(v, list) for v in d.values()
    ) and len({len(v) for v in d.values()}) == 1

Try / catch

try:
    resp = OmniWidgetResponseModel(content=table_dict)
except ValueError as e:
    if "dictionary of lists" in str(e):
        raise ValueError(f"ragged table: { {k: len(v) for k, v in table_dict.items()} }") from e
    raise

Prevention

Build dict-of-lists from a single loop so lengths stay aligned
Assert equal list lengths at construction time
Prefer passing a DataFrame or list of records directly

When it happens

Trigger: Constructing OmniWidgetResponseModel(content={'col_a': [...], 'col_b': [...]}) where list lengths differ (ValueError in pd.DataFrame construction), or the lists contain objects pandas/json cannot encode.

Common situations: Assembling a dict-of-lists from heterogeneous loops where one list ends up shorter or longer; embedding Timestamps, Decimals, or model objects inside the lists; an empty dict {} with other code paths mutating values.

Related errors

AI-assisted analysis of OpenBB-finance/OpenBB@3e071fcc2c (2026-08-14). Data as JSON: /api/errors/a842af14087829f8. Report an issue: GitHub.