带有 Python 3.8 的 Jupyter 笔记本 - NotImplementedError

Question

Upgraded recently to Python 3.8, and installed jupyter . However, when trying to run jupyter notebook getting the following error:

  File "c:\users\user\appdata\local\programs\python\python38\lib\site-packages\tornado\platform\asyncio.py", line 99, in add_handler
    self.asyncio_loop.add_reader(fd, self._handle_events, fd, IOLoop.READ)
  File "c:\users\user\appdata\local\programs\python\python38\lib\asyncio\events.py", line 501, in add_reader
    raise NotImplementedError
NotImplementedError

I know Python 3.8 on windows switched to ProactorEventLoop by default, so I suspect it is related to this.

Jupyter does not support Python 3.8 at the moment? Is there a work around?

Answer 1

EDIT

This issue exists in older versions of Jupyter Notebook and was fixed in version 6.0.3 (released 2020-01-21). To upgrade to the latest version run:

pip install notebook --upgrade

---

Following on this issue through GitHub, it seems the problem is related to the tornado server that jupyter uses.

For those that can't wait for an official fix, I was able to get it working by editing the file tornado/platform/asyncio.py , by adding:

 import sys if sys.platform == 'win32': asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())

After the main imports.

I expect an official fix for this soon, however.

Answer 2

Revising the answer in 2019

Change the end part of the file C:\Users\{USER-NAME}\AppData\Local\Programs\Python\Python38\Lib\asyncio\__init__.py

From

if sys.platform == 'win32':  # pragma: no cover
    from .windows_events import *
    __all__ += windows_events.__all__
else:
    from .unix_events import *  # pragma: no cover
    __all__ += unix_events.__all__

To

import asyncio

if sys.platform == 'win32':
    from .windows_events import *
    asyncio.set_event_loop_policy(asyncio.WindowsSelectorEventLoopPolicy())
    __all__ += windows_events.__all__
else:
    from .unix_events import *  # pragma: no cover
    __all__ += unix_events.__all__

Answer 3

For me, I had to reinstall asyncio

pip install asyncio --upgrade

And upgrade the kernel package

pip install ipykernel --upgrade

Answer 4

I solved this problem by changing the python version from 3.9 to 3.7. (Windows).