Environment:

• NNI version:2.0
• NNI mode (local|remote|pai):local
• Client OS: win10
• Server OS (for remote mode only):
• Python version: 3.7.8
• PyTorch/TensorFlow version: torch 1.7
• Is conda/virtualenv/venv used?: conda
• Is running in Docker?: no

Log message:

• nnimanager.log:
  [2021-02-26 09:43:02] ERROR [ 'Dispatcher error: This socket has been ended by the other party' ]
  [2021-02-26 09:43:02] ERROR [ 'Error: Dispatcher stream error, tuner may have crashed.\n at EventEmitter.dispatcher.onError (d:\anaconda\envs\py_1.7\lib\site-packages\nni_node\core\nnimanager.js:533:32)\n at EventEmitter.emit (events.js:198:13)\n at Socket.IpcInterface.outgoingStream.on (d:\anaconda\envs\py_1.7\lib\site-packages\nni_node\core\ipcInterface.js:42:72)\n at Socket.emit (events.js:198:13)\n at Socket.writeAfterFIN [as write] (net.js:399:8)\n at IpcInterface.sendCommand (d:\anaconda\envs\py_1.7\lib\site-packages\nni_node\core\ipcInterface.js:49:38)\n at NNIManager.pingDispatcher (d:\anaconda\envs\py_1.7\lib\site-packages\nni_node\core\nnimanager.js:378:29)' ]
  [2021-02-26 09:43:02] INFO [ 'Change NNIManager status from: RUNNING to: ERROR' ]
  [2021-02-26 09:43:02] WARNING [ 'Commands jammed in buffer!' ]

• dispatcher.log:
  [2021-02-26 09:42:04] INFO (GP_Tuner_AutoML/Thread-1) Generate paramageters:
  {'layers': 10, 'neurons': 20}
  [2021-02-26 09:42:51] INFO (GP_Tuner_AutoML/Thread-1) Received trial result.
  [2021-02-26 09:42:51] INFO (GP_Tuner_AutoML/Thread-1) value :-0.010340445765208602
  [2021-02-26 09:42:51] INFO (GP_Tuner_AutoML/Thread-1) parameter : {'layers': 10, 'neurons': 20}
  [2021-02-26 09:42:53] WARNING (medianstop_Assessor/Thread-2) trial_end: trial_job_id does not exist in running_history
  [2021-02-26 09:42:53] ERROR (nni.runtime.msg_dispatcher_base/Thread-1) 'str' object has no attribute 'decode'
  Traceback (most recent call last):
  File "D:\anaconda\envs\py_1.7\lib\site-packages\nni\runtime\msg_dispatcher_base.py", line 88, in command_queue_worker
  self.process_command(command, data)
  File "D:\anaconda\envs\py_1.7\lib\site-packages\nni\runtime\msg_dispatcher_base.py", line 147, in process_command
  command_handlerscommand
  File "D:\anaconda\envs\py_1.7\lib\site-packages\nni\runtime\msg_dispatcher.py", line 101, in handle_request_trial_jobs
  params_list = self.tuner.generate_multiple_parameters(ids, st_callback=self.send_trial_callback)
  File "D:\anaconda\envs\py_1.7\lib\site-packages\nni\tuner.py", line 132, in generate_multiple_parameters
  res = self.generate_parameters(parameter_id, **kwargs)
  File "D:\anaconda\envs\py_1.7\lib\site-packages\nni\algorithms\hpo\gp_tuner\gp_tuner.py", line 123, in generate_parameters
  self._gp.fit(self._space.params, self._space.target)
  File "D:\anaconda\envs\py_1.7\lib\site-packages\sklearn\gaussian_process_gpr.py", line 249, in fit
  bounds))
  File "D:\anaconda\envs\py_1.7\lib\site-packages\sklearn\gaussian_process_gpr.py", line 504, in _constrained_optimization
  _check_optimize_result("lbfgs", opt_res)
  File "D:\anaconda\envs\py_1.7\lib\site-packages\sklearn\utils\optimize.py", line 243, in _check_optimize_result
  ).format(solver, result.status, result.message.decode("latin1"))
  AttributeError: 'str' object has no attribute 'decode'
  [2021-02-26 09:42:57] INFO (nni.runtime.msg_dispatcher_base/MainThread) Dispatcher exiting...
  [2021-02-26 09:42:59] INFO (nni.runtime.msg_dispatcher_base/MainThread) Dispatcher terminiated

• nnictl stdout and stderr:

The code worked a month ago. But today it did not. I want to do 100 trials. It will stop in the middle and give me the erroe 'Dispatcher stream error, tuner may have crashed'.