Jupyter Lab 和 Notebook 问题：内核错误

Jupyter Lab and Notebook Problem: Kernel Error

看来我的一个内核不知何故被删除了。也许这就是我收到此错误的原因。我怎么可能修好它？我可以重新安装一些东西吗（也许 base 环境 中的内核）？

如果没有更好的选择，作为最后的手段，我会尝试完全重新安装 anaconda：Default kernel in jupyter notebook (Python3) not working。

我试过使用以下方法：

  1. Installation of Jupyter Lab: requirements already satisfied
  2. Kernels don't show up when runnning "jupyter lab"
  3. UI says "No kernel" while I definitively have one
  4. Getting Kernel Error while running Jupyter Notebook in Python3
  5. https://ipython.readthedocs.io/en/latest/install/kernel_install.html
  6. https://medium.com/flatiron-engineering/recovering-from-a-jupyter-disaster-27401677aeeb

当前内核列表

jupyter kernelspec list

输出：

Available kernels:
  python3    C:\Users\raysu\AppData\Roaming\jupyter\kernels\python3
  vpython    C:\ProgramData\jupyter\kernels\vpython

但是我必须有另一个与我的基本环境关联的内核（我想它不知何故被删除了）。 

C:\Users\raysu\Documents>conda env list
# conda environments:
#
base                  *  C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64
astra_env                C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\envs\astra_env
bokeh_env                C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\envs\bokeh_env
sound_env                C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\envs\sound_env
tf_env                   C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\envs\tf_env
                         C:\Users\raysu\Anaconda3
                         C:\Users\raysu\Anaconda3\envs\pyforge
opencv_env               C:\Users\raysu\AppData\Local\conda\conda\envs\opencv_env
test_env                 C:\Users\raysu\AppData\Local\conda\conda\envs\test_env

错误

Traceback (most recent call last):
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\lib\site-packages\tornado\web.py", line 1699, in _execute
    result = await result
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\lib\site-packages\tornado\gen.py", line 742, in run
    yielded = self.gen.throw(*exc_info)  # type: ignore
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\lib\site-packages\notebook\services\sessions\handlers.py", line 72, in post
    type=mtype))
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\lib\site-packages\tornado\gen.py", line 735, in run
    value = future.result()
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\lib\site-packages\tornado\gen.py", line 742, in run
    yielded = self.gen.throw(*exc_info)  # type: ignore
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\lib\site-packages\notebook\services\sessions\sessionmanager.py", line 88, in create_session
    kernel_id = yield self.start_kernel_for_session(session_id, path, name, type, kernel_name)
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\lib\site-packages\tornado\gen.py", line 735, in run
    value = future.result()
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\lib\site-packages\tornado\gen.py", line 742, in run
    yielded = self.gen.throw(*exc_info)  # type: ignore
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\lib\site-packages\notebook\services\sessions\sessionmanager.py", line 101, in start_kernel_for_session
    self.kernel_manager.start_kernel(path=kernel_path, kernel_name=kernel_name)
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\lib\site-packages\tornado\gen.py", line 735, in run
    value = future.result()
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\lib\site-packages\tornado\gen.py", line 209, in wrapper
    yielded = next(result)
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\lib\site-packages\notebook\services\kernels\kernelmanager.py", line 168, in start_kernel
    super(MappingKernelManager, self).start_kernel(**kwargs)
  File "C:\Users\raysu\AppData\Roaming\Python\Python36\site-packages\jupyter_client\multikernelmanager.py", line 110, in start_kernel
    km.start_kernel(**kwargs)
  File "C:\Users\raysu\AppData\Roaming\Python\Python36\site-packages\jupyter_client\manager.py", line 240, in start_kernel
    self.write_connection_file()
  File "C:\Users\raysu\AppData\Roaming\Python\Python36\site-packages\jupyter_client\connect.py", line 476, in write_connection_file
    kernel_name=self.kernel_name
  File "C:\Users\raysu\AppData\Roaming\Python\Python36\site-packages\jupyter_client\connect.py", line 141, in write_connection_file
    with secure_write(fname) as f:
  File "C:\Program Files (x86)\Microsoft Visual Studio\Shared\Anaconda3_64\lib\contextlib.py", line 81, in __enter__
    return next(self.gen)
  File "C:\Users\raysu\AppData\Roaming\Python\Python36\site-packages\jupyter_core\paths.py", line 404, in secure_write
    win32_restrict_file_to_user(fname)
  File "C:\Users\raysu\AppData\Roaming\Python\Python36\site-packages\jupyter_core\paths.py", line 359, in win32_restrict_file_to_user
    import win32api
ImportError: DLL load failed: The specified procedure could not be found.

Solved the problem by editing the relevant kernelspec: kernel.json file after fresh installation of Anaconda.

详细解决方案

如前所述，我发现我有两个 kernelspecs。 （命令：jupyter kernelspec list）

  1. python3: C:\Users\raysu\AppData\Roaming\jupyter\kernels\python3
  2. vpython: C:\ProgramData\jupyter\kernels\vpython

kernelspec 是一个 .json 文件，它维护 jupyter-notebook/lab 启动某个内核的内核规范。幸运的是，内核 vpython 正在运行，这帮助我缩小了 kernelpsec: python3 中的问题来源。我必须更正 python 可执行文件 (python.exe) 的路径，这才解决了问题。

我想提一下，在这种情况下，以下两个资源派上了用场。在看到 kernelspec 文档的 typical-structure 之后，我更加清楚了问题所在。

注意： 但是，由于我无法验证这个理论，我会请其他有类似问题的人先复制旧的 kernel.json 文件然后更新 python.exe 文件的路径。如果这解决了 内核错误 ，则可能不需要完全重新安装 Anaconda。

Long story short:

如果您的 jupyter notebook/lab 环境向您显示 内核错误，问题的根源很可能在 kernelspec 文件中：kernel.json 和 python.exe 的路径不正确。如果即使在重新安装 anaconda/jupyter-notebook/lab 后相同的 kernel error 仍然存在，这可能是一种更可能的情况。

例如，在我的例子中，python3-kernelspec 位于：

"C:\Users\raysu\AppData\Roaming\jupyter\kernels\python3"

python.exe 位于：

"C:\Users\raysu\Anaconda3\python.exe"

但是，python-可执行文件 的路径是错误的：它仍然显示旧安装的路径。而post-anaconda-reinstallation，这个路径变了。因此，我必须通过编辑 kernel.json 文件来更新 python3 的内核规范。

# kernel.json file
{
 "argv": [
  "C:\Users\raysu\Anaconda3\python.exe",
  "-m",
  "ipykernel_launcher",
  "-f",
  "{connection_file}"
 ],
 "display_name": "Python 3",
 "language": "python"
}

如果这不能解决您的问题，请查阅以下两个文档。我因此浪费了4天。希望这个答案将来能对某人有所帮助。

什么派上用场了？

  1. https://jupyter-notebook.readthedocs.io/en/stable/troubleshooting.html
  2. https://jupyter-client.readthedocs.io/en/stable/kernels.html

我能够解决问题 here

我用这个命令安装了 jupyter_client 5.3.4 和 jupyter_core 4.6.0 

pip install jupyter_client --upgrade