AttributeError: '_UnixSelectorEventLoop' object has no attribute '_signal_handlers'

I've been upgrading our Django/Python app to Python 3.9.7 and Django 3.2.7 (from Python 3.5 and Django 1.11.23).

Currently if I try to run python manage.py createsuperuser

I get the following error

Traceback (most recent call last):
  File "/Users/myuser/.pyenv/versions/3.9.7/lib/python3.9/asyncio/selector_events.py", line 261, in _add_reader
    key = self._selector.get_key(fd)
  File "/Users/myuser/.pyenv/versions/3.9.7/lib/python3.9/selectors.py", line 193, in get_key
    raise KeyError("{!r} is not registered".format(fileobj)) from None
KeyError: '10 is not registered'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/Users/myuser/Development/app/manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/myuser/.pyenv/versions/insta9/lib/python3.9/site-packages/django/core/management/__init__.py", line 419, in execute_from_command_line
    utility.execute()
  File "/Users/myuser/.pyenv/versions/insta9/lib/python3.9/site-packages/django/core/management/__init__.py", line 413, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/myuser/.pyenv/versions/insta9/lib/python3.9/site-packages/django/core/management/base.py", line 367, in run_from_argv
    connections.close_all()
  File "/Users/myuser/.pyenv/versions/insta9/lib/python3.9/site-packages/django/db/utils.py", line 213, in close_all
    connection.close()
  File "/Users/myuser/.pyenv/versions/insta9/lib/python3.9/site-packages/django/utils/asyncio.py", line 19, in inner
    event_loop = asyncio.get_event_loop()
  File "/Users/myuser/.pyenv/versions/3.9.7/lib/python3.9/asyncio/events.py", line 639, in get_event_loop
    self.set_event_loop(self.new_event_loop())
  File "/Users/myuser/.pyenv/versions/3.9.7/lib/python3.9/asyncio/events.py", line 659, in new_event_loop
    return self._loop_factory()
  File "/Users/myuser/.pyenv/versions/3.9.7/lib/python3.9/asyncio/unix_events.py", line 54, in __init__
    super().__init__(selector)
  File "/Users/myuser/.pyenv/versions/3.9.7/lib/python3.9/asyncio/selector_events.py", line 61, in __init__
    self._make_self_pipe()
  File "/Users/myuser/.pyenv/versions/3.9.7/lib/python3.9/asyncio/selector_events.py", line 112, in _make_self_pipe
    self._add_reader(self._ssock.fileno(), self._read_from_self)
  File "/Users/myuser/.pyenv/versions/3.9.7/lib/python3.9/asyncio/selector_events.py", line 263, in _add_reader
    self._selector.register(fd, selectors.EVENT_READ,
  File "/Users/myuser/.pyenv/versions/3.9.7/lib/python3.9/selectors.py", line 523, in register
    self._selector.control([kev], 0, 0)
TypeError: changelist must be an iterable of select.kevent objects
Exception ignored in: <function BaseEventLoop.__del__ at 0x103307310>
Traceback (most recent call last):
  File "/Users/myuser/.pyenv/versions/3.9.7/lib/python3.9/asyncio/base_events.py", line 683, in __del__
    self.close()
  File "/Users/myuser/.pyenv/versions/3.9.7/lib/python3.9/asyncio/unix_events.py", line 63, in close
    if self._signal_handlers:
AttributeError: '_UnixSelectorEventLoop' object has no attribute '_signal_handlers'
Exception ignored in: <function BaseEventLoop.__del__ at 0x103307310>
Traceback (most recent call last):
  File "/Users/myuser/.pyenv/versions/3.9.7/lib/python3.9/asyncio/base_events.py", line 683, in __del__
    self.close()
  File "/Users/myuser/.pyenv/versions/3.9.7/lib/python3.9/asyncio/unix_events.py", line 63, in close
    if self._signal_handlers:
AttributeError: '_UnixSelectorEventLoop' object has no attribute '_signal_handlers'

These are some of the versions I'm using in my requirements.txt

Django==3.2.7
django-braces==1.14.0
django-pipeline==2.0.6
django-storages==1.11.1
djangorestframework==3.12.4
django-localflavor==2.0
django-redis==5.0.0
django_guardian==2.4.0
django-debug-toolbar==3.2.2
django-grappelli==2.15.1
django-extensions==3.1.3
django-simple-history==3.0.0
django-cities-light==3.8.1
django-autoslug==1.9.8
django-constance==2.8.0
django-jsonify==0.3.0
django-bulk-update==2.2.0
django-sslserver==0.22
django-admin-easy==0.6.1
django-admin-rangefilter==0.8.1
django-model-utils==4.1.1
gunicorn==19.7.1
honcho==0.7.1
ipython==5.6.0
eventlet==0.32.0
selenium==2.53.2

This also seems to happen when I runserver, and then kill the server again. Any ideas what could be causing the issue?