REGR: comparing datetime vs None raises

pandas/core/arrays/datetimelike.py

@@ -107,6 +107,7 @@
  algorithms,
  missing,
  nanops,
+ ops,
 )
 from pandas.core.algorithms import (
  checked_add_with_arr,
@@ -947,8 +948,12 @@ def _cmp_method(self, other, op):
 
  dtype = getattr(other, "dtype", None)
  if is_object_dtype(dtype):
- return op(np.asarray(self, dtype=object), other)
-
+ # We have to use comp_method_OBJECT_ARRAY instead of numpy
+ # comparison otherwise it would raise when comparing to None
+ result = ops.comp_method_OBJECT_ARRAY(
+ op, np.asarray(self.astype(object)), other
+ )
+ return result
  if other is NaT:
  if op is operator.ne:
  result = np.ones(self.shape, dtype=bool)

pandas/tests/series/indexing/test_datetime.py

@@ -486,3 +486,12 @@ def test_getitem_str_second_with_datetimeindex():
  msg = r"Timestamp\('2012-01-02 18:01:02-0600', tz='US/Central'\)"
  with pytest.raises(KeyError, match=msg):
  df[df.index[2]]
+
+
+def test_compare_datetime_with_all_none():
+ # GH#54870
+ ser = Series(["2020-01-01", "2020-01-02"], dtype="datetime64[ns]")
+ ser2 = Series([None, None])
+ result = ser > ser2
+ expected = Series([False, False])
+ tm.assert_series_equal(result, expected)