Now where in the world did everything go?

Jupyter/IPython 4.x works differently than IPython 3.x.

In short

• The notebook was split from IPython. You need to install both to run the notebook with IPython now. The easiest way is to use Anaconda and do a conda install jupyter
• There are no profiles anymore. You can specify environment variables to change the default, see Jupyter ML].
• The configuration has moved to a new place. To find out where, see below.
• There is a kind of automatic upgrade of the configuration files from IPython 3.x to Jupyter.

So where can I find things now?

To find where the configuration files are, start IPython

from __future__ import print_function
from jupyter_core.paths import jupyter_config_dir, jupyter_config_path
print(jupyter_config_dir())
print(jupyter_config_path())

jupyter_config_dir() shows you where your local configuration files are, jupyter_config_path shows you where Jupyter will look for configuration files. For the notebook, there are two files that will be used: jupyter_notebook_config.py and jupyter_notebook_config.json.

The nbextension directory has moved to a different location and can be found in one of these directories:

from __future__ import print_function
from jupyter_core.paths import jupyter_data_dir, jupyter_path
print(jupyter_data_dir())
print(jupyter_path())