Why does jupyter display "None not found"?

Question

I am trying to use jupyter to write and edit python code. I have a .ipynb file open, but I see "None not found" in the upper right hand corner and I can't execute any of the code that I write. What's so bizarre is that I'll open other .ipynb files and have no problem. Additionally, when I click on the red "None not found" icon, I'll get the message "The 'None' kernel is not available. Please pick another suitable kernel instead, or install that kernel." I have Python 3.5.2 installed. I suspect the problem is that jupyter is not detecting the Python 3 kernel? It displays "Python[root]" where it should say "Python 3." Does anyone know how to get this fixed?

Screenshot of working code

Screenshot "None not found"

Solution 1

I had the same problem here. The solution for me was:

1. in the menu in Kernel -> Change kernel -> choose Python [Root] (or the kernel you want),
2. save the file,
3. close it,
4. reopen it.

Solution 2

I suspect that that specific .ipynb file contains some metadata specifying a kernel that you do not have installed - see the file format specification.

If you open that file with a text editor and search for metadata you should see something looks like:

{
  "metadata" : {
    "signature": "hex-digest", # used for authenticating unsafe outputs on load
    "kernel_info": {
        # if kernel_info is defined, its name field is required.
        "name" : "the name of the kernel"
    },
    "language_info": {
        # if language_info is defined, its name field is required.
        "name" : "the programming language of the kernel",
        "version": "the version of the language",
        "codemirror_mode": "The name of the codemirror mode to use [optional]"
    }
  },
  "nbformat": 4,
  "nbformat_minor": 0,
  "cells" : [
      # list of cell dictionaries, see below
  ],
}

One option is to change the kernel and language entries to empty dictionaries but you may find that this notebook is actually an iR notebook, or any of several others.

Solution 3

Change kernel Python[Root] Save, close and reopen