BUG: fix AttributeError raised with pd.concat between a None and timezone-aware Timestamp

doc/source/whatsnew/v2.2.0.rst

@@ -301,6 +301,7 @@ Categorical
 
 Datetimelike
 ^^^^^^^^^^^^
+- Bug in :func:`concat` raising ``AttributeError`` when concatenating all-NA DataFrame with :class:`DatetimeTZDtype` dtype DataFrame. (:issue:`52093`)
 - Bug in :meth:`DatetimeIndex.union` returning object dtype for tz-aware indexes with the same timezone but different units (:issue:`55238`)
 - Bug in :meth:`Tick.delta` with very large ticks raising ``OverflowError`` instead of ``OutOfBoundsTimedelta`` (:issue:`55503`)
 - Bug in adding or subtracting a :class:`Week` offset to a ``datetime64`` :class:`Series`, :class:`Index`, or :class:`DataFrame` column with non-nanosecond resolution returning incorrect results (:issue:`55583`)

pandas/core/internals/managers.py

@@ -26,6 +26,7 @@
     BlockPlacement,
     BlockValuesRefs,
 )
+from pandas._libs.tslibs import Timestamp
 from pandas.errors import PerformanceWarning
 from pandas.util._decorators import cache_readonly
 from pandas.util._exceptions import find_stack_level
@@ -2304,7 +2305,8 @@ def _preprocess_slice_or_indexer(
 def make_na_array(dtype: DtypeObj, shape: Shape, fill_value) -> ArrayLike:
     if isinstance(dtype, DatetimeTZDtype):
         # NB: exclude e.g. pyarrow[dt64tz] dtypes
-        i8values = np.full(shape, fill_value._value)
+        ts = Timestamp(fill_value).as_unit(dtype.unit)
+        i8values = np.full(shape, ts._value)
         return DatetimeArray(i8values, dtype=dtype)
 
     elif is_1d_only_ea_dtype(dtype):

pandas/tests/reshape/concat/test_concat.py

@@ -867,3 +867,14 @@ def test_concat_ea_upcast():
     result = concat([df1, df2])
     expected = DataFrame(["a", 1], index=[0, 0])
     tm.assert_frame_equal(result, expected)
+
+
+def test_concat_none_with_timezone_timestamp():
+    # GH#52093
+    df1 = DataFrame([{"A": None}])
+    df2 = DataFrame([{"A": pd.Timestamp("1990-12-20 00:00:00+00:00")}])
+    msg = "The behavior of DataFrame concatenation with empty or all-NA entries"
+    with tm.assert_produces_warning(FutureWarning, match=msg):
+        result = concat([df1, df2], ignore_index=True)
+    expected = DataFrame({"A": [None, pd.Timestamp("1990-12-20 00:00:00+00:00")]})
+    tm.assert_frame_equal(result, expected)