BUG: Fixes Issue pandas-dev#34318

Author: pedrooa

pandas/core/indexing.py

@@ -766,9 +766,11 @@ def _getitem_lowerdim(self, tup: Tuple):
         # ...but iloc should handle the tuple as simple integer-location
         # instead of checking it as multiindex representation (GH 13797)
         if isinstance(ax0, ABCMultiIndex) and self.name != "iloc":
-            result = self._handle_lowerdim_multi_index_axis0(tup)
-            if result is not None:
+            try:
+                result = self._handle_lowerdim_multi_index_axis0(tup)
                 return result
+            except Exception:
+                pass
 
         if len(tup) > self.ndim:
             raise IndexingError("Too many indexers. handle elsewhere")
@@ -816,9 +818,11 @@ def _getitem_nested_tuple(self, tup: Tuple):
             if self.name != "loc":
                 # This should never be reached, but lets be explicit about it
                 raise ValueError("Too many indices")
-            result = self._handle_lowerdim_multi_index_axis0(tup)
-            if result is not None:
+            try:
+                result = self._handle_lowerdim_multi_index_axis0(tup)
                 return result
+            except Exception:
+                pass
 
             # this is a series with a multi-index specified a tuple of
             # selectors
@@ -1065,7 +1069,7 @@ def _handle_lowerdim_multi_index_axis0(self, tup: Tuple):
             if len(tup) <= self.obj.index.nlevels and len(tup) > self.ndim:
                 raise ek
 
-        return None
+        raise Exception("No label returned")
 
     def _getitem_axis(self, key, axis: int):
         key = item_from_zerodim(key)

pandas/tests/series/indexing/test_indexing.py

@@ -853,6 +853,17 @@ def test_setitem_slice_into_readonly_backing_data():
     assert not array.any()
 
 
+def test_access_none_value_in_multiindex():
+    # GH34318: test that you can access a None value using .loc through a Multiindex
+
+    expected = None
+    result = pd.Series([None], pd.MultiIndex.from_arrays([["Level1"], ["Level2"]])).loc[
+        ("Level1", "Level2")
+    ]
+
+    assert expected == result
+
+
 """
 miscellaneous methods
 """