I have installed Jupyter Notebook on ubuntu 16.04 using pip3. I can execute jupyter notebook command. It opens and shows a list of current path directories.
change the ownership of the ~/.local/share/jupyter directory from root to user.
sudo chown -R user:user ~/.local/share/jupyter
see here: https://github.com/ipython/ipython/issues/8997
The first user before the colon is your username, the second user after the colon is your group. If you get chown: [user]: illegal group name, find your group with groups, or specify no group with sudo chown user: ~/.local/share/jupyter.
EDIT: Added -R option in comments to the answer. You have to change ownership of all files inside this directory (or inside ~/.jupyter/, wherever it gives you PermissionError) to your user to make it work.