I am using a Macbook with OS Sierra, and running Python 3.6.1 and Jupyter Notebook Server 5.0.0 I installed Jupyter Notebook extensions, following the instructions as mentioned
I solved this problem by removing jupyter-notebook, jupyter_contrib_nbextensions, and jupyter_nbextensions_configurator, and starting it from scratch.
Note: It only works on Anaconda environment.
For the different source of installation, you can remove these package through:
pip uninstall jupyter
pip uninstall jupyter_contrib_nbextensions
pip uninstall jupyter_nbextensions_configurator
or
conda remove --force jupyter notebook
conda remove --force jupyter_nbextensions_configurator
conda remove --force jupyter_contrib_nbextensions
But I'd advise you to run both of the above commands.
It's better to install all the packages from anaconda:
conda update notebook
conda install jupyter notebook
conda install -c conda-forge jupyter_nbextensions_configurator
conda install -c conda-forge jupyter_contrib_nbextensions