ConnectionResetError: [Errno 104] Connection reset by peer

[cncPomper]

In colab:

!pip install highway-env
!pip install stable-baselines3

import gymnasium as gym
from stable_baselines3 import PPO
from stable_baselines3.common.env_util import make_vec_env
from stable_baselines3.common.vec_env import SubprocVecEnv
from metadrive.envs.metadrive_env import MetaDriveEnv
from metadrive.envs.gym_wrapper import createGymWrapper
import highway_env  # noqa: F401

# ==================================
#        Main script
# ==================================

n_cpu = 6
batch_size = 64
env = make_vec_env("highway-fast-v0", n_envs=n_cpu, vec_env_cls=SubprocVecEnv)
model = PPO(
    "MlpPolicy",
    env,
    policy_kwargs=dict(net_arch=[dict(pi=[256, 256], vf=[256, 256])]),
    n_steps=batch_size * 12 // n_cpu,
    batch_size=batch_size,
    n_epochs=10,
    learning_rate=5e-4,
    gamma=0.8,
    verbose=2,
    tensorboard_log="highway_ppo/",
)
# Train the agent
model.learn(total_timesteps=int(2e4))
# Save the agent
model.save("highway_ppo/model")

model = PPO.load("highway_ppo/model")
env = gym.make("highway-fast-v0")
for _ in range(5):
    obs, info = env.reset()
    done = truncated = False
    while not (done or truncated):
        action, _ = model.predict(obs)
        obs, reward, done, truncated, info = env.step(action)
        env.render()

---------------------------------------------------------------------------
ConnectionResetError                      Traceback (most recent call last)
[<ipython-input-15-736b91dfab08>](https://localhost:8080/#) in <cell line: 0>()
     30 n_cpu = 6
     31 batch_size = 64
---> 32 env = make_vec_env("highway-fast-v0", n_envs=n_cpu, vec_env_cls=SubprocVecEnv)
     33 model = PPO(
     34     "MlpPolicy",

4 frames
[/usr/lib/python3.11/multiprocessing/connection.py](https://localhost:8080/#) in _recv(self, size, read)
    393         remaining = size
    394         while remaining > 0:
--> 395             chunk = read(handle, remaining)
    396             n = len(chunk)
    397             if n == 0:

ConnectionResetError: [Errno 104] Connection reset by peer

Can anyone fix it or explain how it works? Thank you