Error with Algorithm.from_checkpoint() in ray2.10.0

1

Hi,

I was using ray 2.8.0 before but switch to 2.10.0 because I want to try the new API.
I have functional training and evaluation code in ray2.8.0. Now, the training code is still functional in ray2.10.0, but the evaluation code gives me the error below:

Traceback (most recent call last):
  File "ppo_eval.py", line 53, in <module>
    algo = Algorithm.from_checkpoint(CHECKPOINT_PATH)
  File "/home/zhijunz/Software/anaconda3/envs/rl_ray_jax/lib/python3.8/site-packages/ray/rllib/algorithms/algorithm.py", line 350, in from_checkpoint
    state = Algorithm._checkpoint_info_to_algorithm_state(
  File "/home/zhijunz/Software/anaconda3/envs/rl_ray_jax/lib/python3.8/site-packages/ray/rllib/algorithms/algorithm.py", line 3047, in _checkpoint_info_to_algorithm_state
    state = pickle.load(f)
AttributeError: Can't get attribute 'Algorithm._init' on <module 'ray.rllib.algorithms.algorithm' from '/home/zhijunz/Software/anaconda3/envs/rl_ray_jax/lib/python3.8/site-packages/ray/rllib/algorithms/algorithm.py'>

My evaluation code simply load the ckpt like this:

algo = Algorithm.from_checkpoint(CHECKPOINT_PATH)

I tried reinstall ray2.8.0, and the code run normally and is able to load the ckpt trained in ray2.10.0.

Any ideas why I got this error? Thanks!