May 18, 2025 · May 19, 2025 · May 19, 2025 · May 19, 2025 · May 19, 2025 · May 22, 2025
diff --git a/doc/source/whatsnew/v3.0.0.rst b/doc/source/whatsnew/v3.0.0.rst
 - Bug in :meth:`DataFrame.stack` with the new implementation where ``ValueError`` is raised when ``level=[]`` (:issue:`60740`)
 - Bug in :meth:`DataFrame.unstack` producing incorrect results when manipulating empty :class:`DataFrame` with an :class:`ExtentionDtype` (:issue:`59123`)
 - Bug in :meth:`concat` where concatenating DataFrame and Series with ``ignore_index = True`` drops the series name (:issue:`60723`, :issue:`56257`)
 - Bug in :meth:`DataFrame.join` where passing a non-pandas object like a ``polars.DataFrame`` with the ``on=`` parameter raised a misleading error message instead of a ``TypeError``. (:issue:`61434`)

 Sparse
 ^^^^^^
diff --git a/pandas/core/frame.py b/pandas/core/frame.py
                raise ValueError("Other Series must have a name")
            other = DataFrame({other.name: other})

        if on is not None:
            if isinstance(other, Iterable) and not isinstance(
                other, (DataFrame, Series, str, bytes, bytearray)
            ):
                invalid = next(
                    (obj for obj in other if not isinstance(obj, (DataFrame, Series))),
                    None,
                )
                if invalid is not None:
                    raise TypeError(
                        f"Join with 'on={on}' requires a pandas DataFrame or Series, "
                        "or an iterable of such objects as 'other'. Got an "
                        f"invalid element of type {type(invalid).__name__} instead."
                    )
            elif not isinstance(other, (DataFrame, Series)):
                raise TypeError(
                    f"Join with 'on={on}' requires a pandas DataFrame or Series as "
                    "'other'. Got "
                    f"{type(other).__name__} instead."
                )

        if isinstance(other, DataFrame):
            if how == "cross":
                return merge(
diff --git a/pandas/tests/frame/methods/test_join.py b/pandas/tests/frame/methods/test_join.py
    tm.assert_frame_equal(result, expected)


 def test_join_with_invalid_non_pandas_objects_raises_typeerror():
    # GH#61434
    # case - 'other' is an invalid non-pandas object
    df1 = DataFrame(
        {
            "Column2": [10, 20, 30],
            "Column3": ["A", "B", "C"],
            "Column4": ["Lala", "YesYes", "NoNo"],
        }
    )

    class FakeOther:
        def __init__(self):
            self.Column2 = [10, 20, 30]
            self.Column3 = ["A", "B", "C"]

    invalid_other = FakeOther()

    with pytest.raises(TypeError, match="requires a pandas DataFrame or Series"):
        df1.join(invalid_other, on=["Column2", "Column3"], how="inner")

    # 'other' is an iterable with mixed types
    df2 = DataFrame({"Column2": [10, 20, 30], "Column3": ["A", "B", "C"]})
    mixed_iterable = [df2, 42]

    with pytest.raises(TypeError, match="requires a pandas DataFrame or Series"):
        df1.join(mixed_iterable, on=["Column2", "Column3"], how="inner")


 class TestDataFrameJoin:
    def test_join(self, multiindex_dataframe_random_data):
        frame = multiindex_dataframe_random_data
Original file line number	Diff line number	Diff line change
Expand Up		@@ -846,6 +846,7 @@ Reshaping
		- Bug in :meth:`DataFrame.stack` with the new implementation where ``ValueError`` is raised when ``level=[]`` (:issue:`60740`)
		- Bug in :meth:`DataFrame.unstack` producing incorrect results when manipulating empty :class:`DataFrame` with an :class:`ExtentionDtype` (:issue:`59123`)
		- Bug in :meth:`concat` where concatenating DataFrame and Series with ``ignore_index = True`` drops the series name (:issue:`60723`, :issue:`56257`)
		- Bug in :meth:`DataFrame.join` where passing a non-pandas object like a ``polars.DataFrame`` with the ``on=`` parameter raised a misleading error message instead of a ``TypeError``. (:issue:`61434`)

		Sparse
		^^^^^^
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -418,6 +418,35 @@ def test_suppress_future_warning_with_sort_kw(sort):
		tm.assert_frame_equal(result, expected)


		def test_join_with_invalid_non_pandas_objects_raises_typeerror():
		# GH#61434
		# case - 'other' is an invalid non-pandas object
		df1 = DataFrame(
		{
		"Column2": [10, 20, 30],
		"Column3": ["A", "B", "C"],
		"Column4": ["Lala", "YesYes", "NoNo"],
		}
		)

		class FakeOther:
		def __init__(self):
		self.Column2 = [10, 20, 30]
		self.Column3 = ["A", "B", "C"]

		invalid_other = FakeOther()

		with pytest.raises(TypeError, match="requires a pandas DataFrame or Series"):
		df1.join(invalid_other, on=["Column2", "Column3"], how="inner")

		# 'other' is an iterable with mixed types
		df2 = DataFrame({"Column2": [10, 20, 30], "Column3": ["A", "B", "C"]})
		mixed_iterable = [df2, 42]

		with pytest.raises(TypeError, match="requires a pandas DataFrame or Series"):
		df1.join(mixed_iterable, on=["Column2", "Column3"], how="inner")


		class TestDataFrameJoin:
		def test_join(self, multiindex_dataframe_random_data):
		frame = multiindex_dataframe_random_data
Expand Down