[bug] Jupyter Notebook Kernel Error

 Traceback (most recent call last):
      File "E:\Anaconda3\envs\fastai\lib\site-packages\tornado\web.py", line 1512, in _execute
        result = yield result
      File "E:\Anaconda3\envs\fastai\lib\site-packages\tornado\gen.py", line 1055, in run
        value = future.result()
      File "E:\Anaconda3\envs\fastai\lib\site-packages\tornado\concurrent.py", line 238, in result
        raise_exc_info(self._exc_info)
      File "", line 4, in raise_exc_info
      File "E:\Anaconda3\envs\fastai\lib\site-packages\tornado\gen.py", line 1063, in run
        yielded = self.gen.throw(*exc_info)
      File "E:\Anaconda3\envs\fastai\lib\site-packages
otebook\services\sessions\handlers.py", line 73, in post
        type=mtype))
      File "E:\Anaconda3\envs\fastai\lib\site-packages\tornado\gen.py", line 1055, in run
        value = future.result()
      File "E:\Anaconda3\envs\fastai\lib\site-packages\tornado\concurrent.py", line 238, in result
        raise_exc_info(self._exc_info)
      File "", line 4, in raise_exc_info
      File "E:\Anaconda3\envs\fastai\lib\site-packages\tornado\gen.py", line 1063, in run
        yielded = self.gen.throw(*exc_info)
      File "E:\Anaconda3\envs\fastai\lib\site-packages
otebook\services\sessions\sessionmanager.py", line 79, in create_session
        kernel_id = yield self.start_kernel_for_session(session_id, path, name, type, kernel_name)
      File "E:\Anaconda3\envs\fastai\lib\site-packages\tornado\gen.py", line 1055, in run
        value = future.result()
      File "E:\Anaconda3\envs\fastai\lib\site-packages\tornado\concurrent.py", line 238, in result
        raise_exc_info(self._exc_info)
      File "", line 4, in raise_exc_info
      File "E:\Anaconda3\envs\fastai\lib\site-packages\tornado\gen.py", line 1063, in run
        yielded = self.gen.throw(*exc_info)
      File "E:\Anaconda3\envs\fastai\lib\site-packages
otebook\services\sessions\sessionmanager.py", line 92, in start_kernel_for_session
        self.kernel_manager.start_kernel(path=kernel_path, kernel_name=kernel_name)
      File "E:\Anaconda3\envs\fastai\lib\site-packages\tornado\gen.py", line 1055, in run
        value = future.result()
      File "E:\Anaconda3\envs\fastai\lib\site-packages\tornado\concurrent.py", line 238, in result
        raise_exc_info(self._exc_info)
      File "", line 4, in raise_exc_info
      File "E:\Anaconda3\envs\fastai\lib\site-packages\tornado\gen.py", line 307, in wrapper
        yielded = next(result)
      File "E:\Anaconda3\envs\fastai\lib\site-packages
otebook\services\kernels\kernelmanager.py", line 160, in start_kernel
        super(MappingKernelManager, self).start_kernel(**kwargs)
      File "E:\Anaconda3\envs\fastai\lib\site-packages\jupyter_client\multikernelmanager.py", line 110, in start_kernel
        km.start_kernel(**kwargs)
      File "E:\Anaconda3\envs\fastai\lib\site-packages\jupyter_client\manager.py", line 259, in start_kernel
        **kw)
      File "E:\Anaconda3\envs\fastai\lib\site-packages\jupyter_client\manager.py", line 204, in _launch_kernel
        return launch_kernel(kernel_cmd, **kw)
      File "E:\Anaconda3\envs\fastai\lib\site-packages\jupyter_client\launcher.py", line 128, in launch_kernel
        proc = Popen(cmd, **kwargs)
      File "E:\Anaconda3\envs\fastai\lib\subprocess.py", line 709, in __init__
        restore_signals, start_new_session)
      File "E:\Anaconda3\envs\fastai\lib\subprocess.py", line 997, in _execute_child
        startupinfo)
    FileNotFoundError: [WinError 2]  。

기원은fastai 라이브러리를 설치할 때 실행하는 것입니다conda env update 이름 모를 새로운 환경을 만들었다.답변 기준:

python -m ipykernel install --user

but later on i find this does not work when you have multiple environments. Only one environment will have the full executaion of ipython, others still break.
This blog and this doc truly solve the problem.