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"

Answer 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.

Answer 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.