Windows error with Python 2

Process isostructure_search:
Traceback (most recent call last):
  File "C:\Users\BKPoon\software\py27\conda_base\lib\multiprocessing\process.py", line 267, in _bootstrap
    self.run()
  File "C:\Users\BKPoon\software\py27\conda_base\lib\multiprocessing\process.py", line 114, in run
    self._target(*self._args, **self._kwargs)
  File "C:\Users\BKPoon\software\py27\modules\phaser_voyager\command_line\..\src\Voyager\voyager_strategy.py", line 1431, in run_action
    if os.path.exists(self.G.nodes[node]["logger_file"]):
AttributeError: 'Isostructure' object has no attribute 'G'
Pending actions to be exectued: True. Current actions: 0 Max actions: 2