title: TypeError: descriptor '__subclasses__' of 'type' object needs an argument while trying to import rasa_core
body: <p>Trying to run a program that runs perfectly fine on my local machine, but on AWS I'm getting: <code>TypeError: descriptor '__subclasses__' of 'type' object needs an argument</code>.
  My pip3 isn't upgraded to the latest version, but that shouldn't be causing an issue since I have downloaded the latest version of rasa_core.</p>
  
  <p>Tried re-installing rasa_core using pip3 -u rasa_core, also tried appending the command with sudo.
  This is the error I get, can someone please help</p>
  
  <pre><code>Traceback (most recent call last):
    File "&lt;stdin&gt;", line 1, in &lt;module&gt;
    File "/home/ubuntu/.local/lib/python3.5/site-packages/rasa_core/__init__.py", line 5, in &lt;module&gt;
      from rasa_core.train import train
    File "/home/ubuntu/.local/lib/python3.5/site-packages/rasa_core/train.py", line 11, in &lt;module&gt;
      from rasa_core.domain import TemplateDomain
    File "/home/ubuntu/.local/lib/python3.5/site-packages/rasa_core/domain.py", line 12, in &lt;module&gt;
      from rasa_core.actions import Action, action
    File "/home/ubuntu/.local/lib/python3.5/site-packages/rasa_core/actions/__init__.py", line 1, in &lt;module&gt;
      from rasa_core.actions.action import Action
    File "/home/ubuntu/.local/lib/python3.5/site-packages/rasa_core/actions/action.py", line 9, in &lt;module&gt;
      from rasa_core import events
    File "/home/ubuntu/.local/lib/python3.5/site-packages/rasa_core/events/__init__.py", line 73, in &lt;module&gt;
      class Event(object):
    File "/home/ubuntu/.local/lib/python3.5/site-packages/rasa_core/events/__init__.py", line 94, in Event
      default: Optional[Type['Event']] = None
    File "/usr/lib/python3.5/typing.py", line 649, in __getitem__
      return Union[arg, type(None)]
    File "/usr/lib/python3.5/typing.py", line 552, in __getitem__
      dict(self.__dict__), parameters, _root=True)
    File "/usr/lib/python3.5/typing.py", line 512, in __new__
      for t2 in all_params - {t1} if not isinstance(t2, TypeVar)):
    File "/usr/lib/python3.5/typing.py", line 512, in &lt;genexpr&gt;
      for t2 in all_params - {t1} if not isinstance(t2, TypeVar)):
    File "/usr/lib/python3.5/typing.py", line 1077, in __subclasscheck__
      if super().__subclasscheck__(cls):
    File "/usr/lib/python3.5/abc.py", line 225, in __subclasscheck__
      for scls in cls.__subclasses__():
  TypeError: descriptor '__subclasses__' of 'type' object needs an argument
  </code></pre>
  
  <p>Can someone please help.</p>