Error: `callbacks` must be a callable method that returns a subclass of DefaultCallbacks, got <class 'ray.rllib.agents.callbacks.DefaultCallbacks'>
问题 when I run some codes(DDPG - Deep Deterministic Policy Gradient), this error occurred: ValueError: callbacks must be a callable method that returns a subclass of DefaultCallbacks, got <class 'ray.rllib.agents.callbacks.DefaultCallbacks'> my code is here: import json def load_policy(): log_dir = "/root/ray_results/DDPG_SimpleSupplyChain_2020-07-15_02-37-48j2fjk67_" # this path needs to be set manually checkpoint_id = "200" with open(f"{log_dir}/params.json", "r") as read_file: config = json