BUG: Fix issue with datetime[ns, tz] input in Block.setitem GH32395

doc/source/whatsnew/v1.0.2.rst

@@ -23,6 +23,7 @@ Fixed regressions
 - Fixed regression where :func:`read_pickle` raised a ``UnicodeDecodeError`` when reading a py27 pickle with :class:`MultiIndex` column (:issue:`31988`).
 - Fixed regression in :class:`DataFrame` arithmetic operations with mis-matched columns (:issue:`31623`)
 - Fixed regression in :meth:`GroupBy.agg` calling a user-provided function an extra time on an empty input (:issue:`31760`)
+- Fixed regression in :meth:`DataFrame.loc`, :meth:`Series.loc` throwing an error when a ``datetime64[ns, tz]`` value is provided (:issue:`32395`)
 - Joining on :class:`DatetimeIndex` or :class:`TimedeltaIndex` will preserve ``freq`` in simple cases (:issue:`32166`)
 -
 

pandas/core/internals/blocks.py

@@ -839,6 +839,9 @@ def setitem(self, indexer, value):
 
         # coerce if block dtype can store value
         values = self.values
+        if is_object_dtype(values.dtype) and isinstance(value, DatetimeArray):
+            value = value.astype(object)
+
         if self._can_hold_element(value):
             # We only get here for non-Extension Blocks, so _try_coerce_args
             #  is only relevant for DatetimeBlock and TimedeltaBlock

pandas/tests/indexing/test_loc.py

@@ -1,4 +1,5 @@
 """ test label based indexing with loc """
+from datetime import timezone
 from io import StringIO
 import re
 
@@ -1015,3 +1016,42 @@ def test_loc_slice_disallows_positional():
     with tm.assert_produces_warning(FutureWarning):
         # GH#31840 deprecated incorrect behavior
         df.loc[1:3, 1] = 2
+
+
+def test_loc_setitem_df_datetime64tz_column_with_index():
+    df = pd.DataFrame(
+        pd.date_range("2020-01-01", "2020-01-06", 6, tz=timezone.utc), columns=["data"]
+    )
+    df2 = pd.DataFrame(index=df.index)
+    df2.loc[df.index, "data"] = df["data"]
+    tm.assert_numpy_array_equal(np.array(df.data), np.array(df2.data))
+    assert df2.data.dtype == np.object
+
+
+def test_loc_setitem_df_datetime64tz_column_without_index():
+    df = pd.DataFrame(
+        pd.date_range("2020-01-01", "2020-01-06", 6, tz=timezone.utc), columns=["data"]
+    )
+    df2 = pd.DataFrame(index=df.index)
+    df2.loc[:, "data"] = df["data"]
+    tm.assert_series_equal(df.data, df2.data)
+
+
+def test_loc_setitem_series_datetime64tz_with_index():
+    s1 = pd.Series(
+        pd.date_range("2020-01-01", "2020-01-06", 6, tz=timezone.utc), name="data"
+    )
+    s2 = pd.Series(index=s1.index, dtype=np.object, name="data")
+    s2.loc[s1.index] = s1
+    tm.assert_numpy_array_equal(np.array(s1), np.array(s2))
+    assert s2.dtype == np.object
+
+
+def test_loc_setitem_series_datetime64tz_without_index():
+    s1 = pd.Series(
+        pd.date_range("2020-01-01", "2020-01-06", 6, tz=timezone.utc), name="data"
+    )
+    s2 = pd.Series(index=s1.index, dtype=np.object, name="data")
+    s2.loc[:] = s1
+    tm.assert_numpy_array_equal(np.array(s1), np.array(s2))
+    assert s2.dtype == np.object