Why does jupyter display "None not found"?

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

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

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.

Change kernel Python[Root]Save, close and reopen