Adjust n_iter: The total number of hyperparameter combinations is 3×3×3×3=813×3×3×3=81. Since this is smaller than n_iter=500, reduce n_iter to 81 or less.

Fix booster Parameter: If you are explicitly setting a booster, ensure it is one of the valid types ('gbtree', 'gblinear', or 'dart'). Disable Deprecated Label Encoder: Pass use_label_encoder=False to XGBClassifier to suppress the warning. Validate Parameter Names: Double-check that all hyperparameter names are valid for XGBClassifier.