单击这么多次后，Jupyter 未从 anaconda 导航器启动，我收到此错误

Question

After installing Jupyter, it is not launching from anaconda navigator after clicking multiples times but still, I get this following error:

Traceback (most recent call last):
File "C:\Users\ising\anaconda3\envs\ml_python_2020\lib\site-packages\jupyterlab_server\server.py", line 20, in 
from notebook.notebookapp import aliases, flags, NotebookApp as ServerApp

File "C:\Users\ising\anaconda3\envs\ml_python_2020\lib\site-packages\notebook\notebookapp.py", line 51, in 
from zmq.eventloop import ioloop

File "C:\Users\ising\AppData\Roaming\Python\Python38\site-packages\zmq\__init__.py", line 50, in 
from zmq import backend

File "C:\Users\ising\AppData\Roaming\Python\Python38\site-packages\zmq\backend\__init__.py", line 40, in 
reraise(*exc_info)

File "C:\Users\ising\AppData\Roaming\Python\Python38\site-packages\zmq\utils\sixcerpt.py", line 34, in reraise
raise value

File "C:\Users\ising\AppData\Roaming\Python\Python38\site-packages\zmq\backend\__init__.py", line 27, in 
_ns = select_backend(first)

File "C:\Users\ising\AppData\Roaming\Python\Python38\site-packages\zmq\backend\select.py", line 28, in select_backend
mod = __import__(name, fromlist=public_api)

File "C:\Users\ising\AppData\Roaming\Python\Python38\site-packages\zmq\backend\cython\__init__.py", line 6, in 
from . import (constants, error, message, context,

ImportError: cannot import name 'constants' from partially initialized module 'zmq.backend.cython' (most likely due to a circular import) (C:\Users\ising\AppData\Roaming\Python\Python38\site-packages\zmq\backend\cython\__init__.py)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:\Users\ising\anaconda3\envs\ml_python_2020\Scripts\jupyter-lab-script.py", line 5, in 
from jupyterlab.labapp import main

File "C:\Users\ising\anaconda3\envs\ml_python_2020\lib\site-packages\jupyterlab\labapp.py", line 14, in 
from jupyterlab_server import slugify, WORKSPACE_EXTENSION

File "C:\Users\ising\anaconda3\envs\ml_python_2020\lib\site-packages\jupyterlab_server\__init__.py", line 4, in 
from .app import LabServerApp

File "C:\Users\ising\anaconda3\envs\ml_python_2020\lib\site-packages\jupyterlab_server\app.py", line 9, in 
from .server import ServerApp

File "C:\Users\ising\anaconda3\envs\ml_python_2020\lib\site-packages\jupyterlab_server\server.py", line 26, in 
from jupyter_server.base.handlers import ( # noqa
ModuleNotFoundError: No module named 'jupyter_server'

Answer 1

You just need to do this step

pip uninstall pyzmq

and after that

pip install pyzmq

go back to your anaconda-navigator and try to launch Jupyter lab and it'll work fine