GH-52093 : AttributeError raised with pd.concat between a None and Timestamp

doc/source/whatsnew/v2.1.0.rst

@@ -207,6 +207,7 @@ Bug fixes
 Categorical
 ^^^^^^^^^^^
 - Bug in :meth:`Series.map` , where the value of the ``na_action`` parameter was not used if the series held a :class:`Categorical` (:issue:`22527`).
+- Bug in :meth:`pd.concat` where an ``AttributeError`` raised with a None and Timestamp (:issue:`52093`)
 -
 
 Datetimelike

pandas/core/internals/concat.py

@@ -512,7 +512,7 @@ def get_reindexed_values(self, empty_dtype: DtypeObj, upcasted_na) -> ArrayLike:
 
                 if isinstance(empty_dtype, DatetimeTZDtype):
                     # NB: exclude e.g. pyarrow[dt64tz] dtypes
-                    i8values = np.full(self.shape, fill_value._value)
+                    i8values = np.full(self.shape, NaT.value)
                     return DatetimeArray(i8values, dtype=empty_dtype)
 
                 elif is_1d_only_ea_dtype(empty_dtype):

pandas/tests/reshape/concat/test_concat.py

@@ -802,3 +802,14 @@ def test_concat_mismatched_keys_length():
         concat((x for x in sers), keys=(y for y in keys), axis=1)
     with tm.assert_produces_warning(FutureWarning, match=msg):
         concat((x for x in sers), keys=(y for y in keys), axis=0)
+
+
+def test_concat_none_to_dttz():
+    # GH-52093
+    data = [{"A": None}]
+    df = DataFrame(data)
+    data_2 = [{"A": [pd.to_datetime("1990-12-20 00:00:00+00:00")]}]
+    df_2 = DataFrame(data_2)
+    result = concat([df, df_2])
+    expected = DataFrame({"A": pd.to_datetime("1990-12-20 00:00:00+00:00")})
+    tm.assert_frame_equal(result, expected)