Fixing Jupyter Notebook startup error

I previously wrote about Jupyter Notebooks here.

Before the MacOS Sierra 10.12.5 update, to launch Jupyter in your browser, you only needed to do this:

  1. Open Terminal.
  2. Enter the desired directory.
  3. Activate your virtualenv (if using one).
  4. At the command line, type:
jupyter notebook

A new window would open in your default web browser, and there were all your Jupyter files.

But after the MacOS update, instead we got an execution error: localhost doesn’t understand the “open location” message. And the browser window did not open.

The way to fix it (do it once) is here.

Note: In the config file, I had to search for 

#c.NotebookApp.browser =

instead of the string the author provided.

Jupyter Notebooks

To install: Install (instructions at Note that pip or pip3 install works. It’s on that page, after the Anaconda part.

You do not have to use Anaconda, which installs a lot of extra things.

You can install into a virtualenv.

After installing (with virtualenv activated, if you installed it that way), in Terminal, at bash prompt:

jupyter notebook

On Mac OS and Chrome, a new browser tab opens automatically, and you’re in the same folder where you were in the Terminal. If you have someone else’s notebook or a folder full of notebooks, you can toss them into that folder using Finder, just like any files.

Screenshot: Jupyter Notebook

Above: Two folders and one notebook file. Below: A notebook, open for work.

Screenshot: Jupyter Notebook

Create a new notebook file: The New button is on the far right side.

The thing I find hard to remember: You have to press Shift-Return to run the code in one of the boxes, or to save markdown you wrote. On the Cell menu, there’s an option to Run All.

Menus and icons: Very self-explanatory. Explore them.

File menu: “Revert to checkpoint” lets you roll back to the previous save.

File menu: “Close and Halt.” Saves the current notebook file and closes it.

To quit Jupyter, go to the Terminal and Control-C (not Command).