added change to whatsnew doc and also changed the logic to raise the …

…ValueError only if its a Dataframe and not for a Series

doc/source/whatsnew/v3.0.0.rst

@@ -65,6 +65,7 @@ Other enhancements
 - :class:`Rolling` and :class:`Expanding` now support aggregations ``first`` and ``last`` (:issue:`33155`)
 - :func:`read_parquet` accepts ``to_pandas_kwargs`` which are forwarded to :meth:`pyarrow.Table.to_pandas` which enables passing additional keywords to customize the conversion to pandas, such as ``maps_as_pydicts`` to read the Parquet map data type as python dictionaries (:issue:`56842`)
 - :meth:`.DataFrameGroupBy.transform`, :meth:`.SeriesGroupBy.transform`, :meth:`.DataFrameGroupBy.agg`, :meth:`.SeriesGroupBy.agg`, :meth:`.SeriesGroupBy.apply`, :meth:`.DataFrameGroupBy.apply` now support ``kurt`` (:issue:`40139`)
+- :meth:`DataFrame.to_json` with ``orient="table"`` now raises a ``ValueError`` if column names are not strings (:issue:`19129`).
 - :meth:`DataFrameGroupBy.transform`, :meth:`SeriesGroupBy.transform`, :meth:`DataFrameGroupBy.agg`, :meth:`SeriesGroupBy.agg`, :meth:`RollingGroupby.apply`, :meth:`ExpandingGroupby.apply`, :meth:`Rolling.apply`, :meth:`Expanding.apply`, :meth:`DataFrame.apply` with ``engine="numba"`` now supports positional arguments passed as kwargs (:issue:`58995`)
 - :meth:`Rolling.agg`, :meth:`Expanding.agg` and :meth:`ExponentialMovingWindow.agg` now accept :class:`NamedAgg` aggregations through ``**kwargs`` (:issue:`28333`)
 - :meth:`Series.map` can now accept kwargs to pass on to func (:issue:`59814`)

pandas/core/generic.py

@@ -2593,7 +2593,9 @@ def to_json(
         """
 
         if orient == "table":
-            if any(isinstance(col, (int, float)) for col in self.columns):
+            if hasattr(self, "columns") and any(
+                isinstance(col, (int, float)) for col in self.columns
+            ):
                 raise ValueError(
                     "Column names must be strings for JSON serialization with "
                     "orient='table'."