TypeError: a bytes-like object is required, not ‘NoneType‘

TypeError                                 Traceback (most recent call last)
~/baselines/general/chainerrl/baselines/ppo.py in <module>
    238 
    239 if __name__ == '__main__':
--> 240     main()

~/baselines/general/chainerrl/baselines/ppo.py in main()
    103 
    104     try:
--> 105         _main(args)
    106     except:  # noqa
    107         logger.exception('execution failed.')

~/baselines/general/chainerrl/baselines/ppo.py in _main(args)
    230             outdir=args.outdir, eval_env=eval_env,
    231             step_hooks=[lr_decay_hook, clip_eps_decay_hook],
--> 232             save_best_so_far_agent=True,
    233         )
    234 

~/opt/anaconda3/lib/python3.7/site-packages/chainerrl/experiments/train_agent.py in train_agent_with_evaluation(agent, env, steps, eval_n_steps, eval_n_episodes, eval_interval, outdir, checkpoint_freq, train_max_episode_len, step_offset, eval_max_episode_len, eval_env, successful_score, step_hooks, save_best_so_far_agent, logger)
    158         successful_score=successful_score,
    159         step_hooks=step_hooks,
--> 160         logger=logger)

~/opt/anaconda3/lib/python3.7/site-packages/chainerrl/experiments/train_agent.py in train_agent(agent, env, steps, outdir, checkpoint_freq, max_episode_len, step_offset, evaluator, successful_score, step_hooks, logger)
     71                 episode_idx += 1
     72                 episode_len = 0
---> 73                 obs = env.reset()
     74                 r = 0
     75             if checkpoint_freq and t % checkpoint_freq == 0:

~/opt/anaconda3/lib/python3.7/site-packages/gym-0.17.2-py3.7.egg/gym/core.py in reset(self, **kwargs)
    280 class ActionWrapper(Wrapper):
    281     def reset(self, **kwargs):
--> 282         return self.env.reset(**kwargs)
    283 
    284     def step(self, action):

~/opt/anaconda3/lib/python3.7/site-packages/gym-0.17.2-py3.7.egg/gym/core.py in reset(self, **kwargs)
    255 class ObservationWrapper(Wrapper):
    256     def reset(self, **kwargs):
--> 257         observation = self.env.reset(**kwargs)
    258         return self.observation(observation)
    259 

~/opt/anaconda3/lib/python3.7/site-packages/gym-0.17.2-py3.7.egg/gym/core.py in reset(self, **kwargs)
    255 class ObservationWrapper(Wrapper):
    256     def reset(self, **kwargs):
--> 257         observation = self.env.reset(**kwargs)
    258         return self.observation(observation)
    259 

~/opt/anaconda3/lib/python3.7/site-packages/gym-0.17.2-py3.7.egg/gym/core.py in reset(self, **kwargs)
    255 class ObservationWrapper(Wrapper):
    256     def reset(self, **kwargs):
--> 257         observation = self.env.reset(**kwargs)
    258         return self.observation(observation)
    259 

~/opt/anaconda3/lib/python3.7/site-packages/chainerrl/wrappers/continuing_time_limit.py in reset(self)
     38     def reset(self):
     39         self._elapsed_steps = 0
---> 40         return self.env.reset()

~/opt/anaconda3/lib/python3.7/site-packages/minerl/env/core.py in reset(self)
    480 
    481             while not self.done:
--> 482                 self.done = self._quit_episode()
    483 
    484                 if not self.done:

~/opt/anaconda3/lib/python3.7/site-packages/minerl/env/core.py in _quit_episode(self)
    582         comms.send_message(self.client_socket, "<Quit/>".encode())
    583         reply = comms.recv_message(self.client_socket)
--> 584         ok, = struct.unpack('!I', reply)
    585         return ok != 0
    586 

TypeError: a bytes-like object is required, not 'NoneType'