reflex-dev/reflex · error · ValueError

Serialized dataframe should be a dict.

Error message

Serialized dataframe should be a dict.

What it means

Internally, data_table serializes a pandas DataFrame via serialize(), expecting a dict with 'data' and 'columns' keys. If a custom serializer or DataFrame format returns something else, this invariant error fires.

Source

Thrown at packages/reflex-components-gridjs/src/reflex_components_gridjs/datatable.py:123

        """
        return {"": "gridjs/dist/theme/mermaid.css"}

    def _render(self) -> Tag:
        if isinstance(self.data, Var) and types.is_dataframe(self.data._var_type):
            self.columns = self.data._replace(
                _js_expr=f"{self.data._js_expr}.columns",
                _var_type=list[Any],
            )
            self.data = self.data._replace(
                _js_expr=f"{self.data._js_expr}.data",
                _var_type=list[list[Any]],
            )
        if types.is_dataframe(type(self.data)):
            # If given a pandas df break up the data and columns
            data = serialize(self.data)
            if not isinstance(data, dict):
                msg = "Serialized dataframe should be a dict."
                raise ValueError(msg)
            self.columns = LiteralVar.create(data["columns"])
            self.data = LiteralVar.create(data["data"])

        # Render the table.
        return super()._render()

View on GitHub (pinned to 45b8ed5ab7)

Solutions

1. Pass a vanilla pandas DataFrame (convert subclasses via pd.DataFrame(df))
2. Or pre-convert: pass data=df.to_dict('records') style list plus explicit columns
3. Check for mismatched reflex package versions and uv sync
4. Report upstream if a plain DataFrame triggers it

Example fix

# before
rx.data_table(data=CustomDF subclass_instance)
# after
rx.data_table(data=pd.DataFrame(subclass_instance))

from reflex.utils import serialize
assert isinstance(serialize(pd.DataFrame(df)), dict), 'unexpected serializer output'

try:
    comp = rx.data_table(data=df)
except ValueError as e:
    if 'Serialized dataframe' in str(e):
        comp = rx.data_table(data=df.to_dict('records'), columns=list(df.columns))
    else:
        raise

When it happens

Trigger: Passing a DataFrame whose serialize() output is not a dict — e.g. a custom pandas subclass or overridden serialization hook in the app.

Common situations: Rare; usually caused by using non-standard DataFrame wrappers or an incompatible reflex/radix serialization version.

Related errors

• The component `{child_name}` can only be a child of the comp
• Cannot serialize color that contains non-literal vars.
• Color is not a valid color.
• No valid JSON representation for {self}
• The keys and values of the object must be literal vars to ge

AI-assisted analysis of reflex-dev/reflex@45b8ed5ab7 (2026-08-28). Data as JSON: /api/errors/935c5e1e41d0ee1e. Report an issue: GitHub.