title: ImportError: cannot import name 'ensure_dir_exists'
body: <p>I update the Jupyter notebook from the old version to latest 5.3.1. However, when I try to launch the notebook from anaconda, it throws an import error:
  I tried to remove and install Jupyter package, still, the issue persists.</p>
  
  <pre><code>Traceback (most recent call last):
  File "C:\Users\v-kangsa\AppData\Local\Continuum\anaconda3\Scripts\jupyter-notebook-script.py", line 6, in 
  from notebook.notebookapp import main
  File "C:\Users\v-kangsa\AppData\Local\Continuum\anaconda3\lib\site-packages\notebook\__init__.py", line 25, in 
  from .nbextensions import install_nbextension
  File "C:\Users\v-kangsa\AppData\Local\Continuum\anaconda3\lib\site-packages\notebook\nbextensions.py", line 27, in 
  from jupyter_core.utils import ensure_dir_exists
  ImportError: cannot import name 'ensure_dir_exists'
  </code></pre>