Because we don't check for an estimator to be `None` in `sample_weight` support, `fit` is failing`. ```python X, y = load_iris(return_X_y=True) voter = VotingClassifier( estimators=[('lr', LogisticRegression()), ('rf', RandomForestClassifier())] ) voter.fit(X, y, sample_weight=np.ones(y.shape)) voter.set_params(lr=None) voter.fit(X, y, sample_weight=np.ones(y.shape)) ``` ``` AttributeError: 'NoneType' object has no attribute 'fit' ```