ERR: User-facing AssertionError in DataFrame Constructor

pandas/core/internals/construction.py

@@ -424,8 +424,13 @@ def _list_to_arrays(data, columns, coerce_float=False, dtype=None):
     else:
         # list of lists
         content = list(lib.to_object_array(data).T)
-    return _convert_object_array(content, columns, dtype=dtype,
-                                 coerce_float=coerce_float)
+    # gh-26429 do not raise user-facing AssertionError
+    try:
+        result = _convert_object_array(content, columns, dtype=dtype,
+                                       coerce_float=coerce_float)
+    except AssertionError as e:
+        raise ValueError(e) from e
+    return result
 
 
 def _list_of_series_to_arrays(data, columns, coerce_float=False, dtype=None):

pandas/tests/frame/test_constructors.py

@@ -435,6 +435,11 @@ def test_constructor_error_msgs(self):
         with pytest.raises(ValueError, match=msg):
             DataFrame(np.random.rand(2, 3), columns=['A', 'B'], index=[1, 2])
 
+        # gh-26429
+        msg = "2 columns passed, passed data had 10 columns"
+        with pytest.raises(ValueError, match=msg):
+            DataFrame((range(10), range(10, 20)), columns=('ones', 'twos'))
+
         msg = ("If using all scalar "
                "values, you must pass "
                "an index")

pandas/tests/io/json/test_pandas.py

@@ -353,7 +353,7 @@ def test_frame_from_json_bad_data(self):
                         '"index":["1","2","3"],'
                         '"data":[[1.0,"1"],[2.0,"2"],[null,"3"]]}')
         msg = "3 columns passed, passed data had 2 columns"
-        with pytest.raises(AssertionError, match=msg):
+        with pytest.raises(ValueError, match=msg):
             read_json(json, orient="split")
 
         # bad key