Jupyter Notebook启动失败：ModuleNotFoundError(tornado.netutil缺失)

问题详情 #

执行启动命令：

(base) me518@PHS024636 ~ % conda activate mageckenv
(mageckenv) me518@PHS024636 ~ % jupyter notebook

触发如下报错：

Traceback (most recent call last):
  File "/Users/me518/miniconda3/envs/mageckenv/bin/jupyter-notebook", line 5, in <module>
    from notebook.notebookapp import main
  File "/Users/me518/miniconda3/envs/mageckenv/lib/python3.7/site-packages/notebook/notebookapp.py", line 59, in <module>
    from tornado import httpserver
  File "/Users/me518/miniconda3/envs/mageckenv/lib/python3.7/site-packages/tornado/httpserver.py", line 32, in <module>
    from tornado.http1connection import HTTP1ServerConnection, HTTP1ConnectionParameters
  File "/Users/me518/miniconda3/envs/mageckenv/lib/python3.7/site-packages/tornado/http1connection.py", line 34, in <module>
    from tornado import iostream
  File "/Users/me518/miniconda3/envs/mageckenv/lib/python3.7/site-packages/tornado/iostream.py", line 40, in <module>
    from tornado.netutil import ssl_wrap_socket, _client_ssl_defaults, _server_ssl_defaults
ModuleNotFoundError: No module named 'tornado.netutil'

已尝试切换所有conda环境，问题仍未解决。

问题原因 #

• Tornado包损坏/版本不兼容：tornado.netutil是Tornado库的核心模块，文件缺失、损坏，或是版本与Python3.7/Jupyter的依赖不匹配，都会导致该报错。
• Conda环境依赖污染：环境间的依赖交叉覆盖，或是全局Jupyter配置调用了错误的包路径，即使切换环境也无法解决问题。

解决办法 #

1. 重装适配版本的Tornado #

激活目标环境后，先卸载现有Tornado，再安装Python3.7兼容的稳定版本：

conda activate mageckenv
# 用pip卸载重装
pip uninstall tornado -y
pip install tornado==5.1.1  # 该版本适配Python3.7，也可尝试6.x兼容版本

或用conda操作：

conda activate mageckenv
conda remove tornado -y
conda install tornado=5.1.1

2. 修复Jupyter Notebook依赖 #

若重装Tornado无效，可重新安装Jupyter Notebook以修复依赖链：

conda activate mageckenv
pip uninstall jupyter notebook -y
pip install jupyter notebook

3. 排查环境路径冲突 #

先确认当前环境的Python和包路径是否正确：

conda activate mageckenv
which python
pip list | grep tornado

如果Python路径不是/Users/me518/miniconda3/envs/mageckenv/bin/python，说明存在路径污染。可尝试重启终端后重新激活环境，或创建全新环境：

conda create -n new_mageckenv python=3.7
conda activate new_mageckenv
pip install jupyter notebook mageck  # 按需安装所需工具包

内容的提问来源于stack exchange，提问作者Minja Velimirovic