BUG: fix .loc.__setitem__ not raising when using too many indexers

Author: DriesSchaumont

pandas/core/indexing.py

@@ -652,8 +652,7 @@ def _get_setitem_indexer(self, key):
                 return ax.get_loc(key)
 
         if isinstance(key, tuple):
-            with suppress(IndexingError):
-                return self._convert_tuple(key)
+            return self._convert_tuple(key)
 
         if isinstance(key, range):
             return list(key)
@@ -911,7 +910,7 @@ def _getitem_nested_tuple(self, tup: tuple):
                 #  we are only getting non-hashable tuples, in particular ones
                 #  that themselves contain a slice entry
                 # See test_loc_series_getitem_too_many_dimensions
-                raise ValueError("Too many indices")
+                raise IndexingError("Too many indexers")
 
             # this is a series with a multi-index specified a tuple of
             # selectors

pandas/tests/indexing/test_loc.py

@@ -2715,6 +2715,13 @@ def test_loc_getitem_multiindex_tuple_level():
     assert result2 == 6
 
 
+def test_loc_setitem_indexer_length():
+    df = DataFrame({"a": [10]})
+    msg = "Too many indexers"
+    with pytest.raises(IndexingError, match=msg):
+        df["a"].loc[0, 0] = 1000
+
+
 class TestLocSeries:
     @pytest.mark.parametrize("val,expected", [(2 ** 63 - 1, 3), (2 ** 63, 4)])
     def test_loc_uint64(self, val, expected):
@@ -2889,11 +2896,11 @@ def test_loc_series_getitem_too_many_dimensions(self, indexer):
             index=MultiIndex.from_tuples([("A", "0"), ("A", "1"), ("B", "0")]),
             data=[21, 22, 23],
         )
-        msg = "Too many indices"
-        with pytest.raises(ValueError, match=msg):
+        msg = "Too many indexers"
+        with pytest.raises(IndexingError, match=msg):
             ser.loc[indexer, :]
 
-        with pytest.raises(ValueError, match=msg):
+        with pytest.raises(IndexingError, match=msg):
             ser.loc[indexer, :] = 1
 
     def test_loc_setitem(self, string_series):