WARNING: Pygments lexer name 'ipython3' is not known

[ostrokach]

I get thousands of warnings:

WARNING: Pygments lexer name 'ipython3' is not known

when I run make html after adding 'nbsphinx' to extensions.

This happens even with an empty index.rst file (it seems to find my .ipynb_checkpoints folder).

---

python 3.5.1
ipython 4.1.1
nbconvert 4.1.0
jupyter 1.0.0
pygments 2.1

[mgeier]

Hmm, for me this has always worked; the lexer should be part of the "IPython" package: http://ipython.readthedocs.org/en/stable/development/lexer.html.

Can you try to re-install this package?

This happens even with an empty index.rst file (it seems to find my .ipynb_checkpoints folder).

Yes, Sphinx searches the whole source directory (including subfolders) for notebook files and parses all of them, regardless of what's in your index.rst. You should probably add something like this to your conf.py:

exclude_patterns = ['_build', '**.ipynb_checkpoints']

See http://nbsphinx.readthedocs.org/en/latest/usage.html.

[ostrokach]

I had to add 'IPython.sphinxext.ipython_console_highlighting' to extensions in my conf.py. Somehow the old IPython docs have this info but the new ones don't.

Adding '**.ipynb_checkpoints' to exclude_patterns fixed the other problem.

Thanks!

[mgeier]

Good to know that you found a solution that works for you!

But still, IMHO the ipython3 lexer should work automatically.
I've never used ipython_console_highlighting (or anything else) explicitly and it just works.
I think this should be somehow be automatically registered when installing the IPython package.

[nehalecky]

FWIW: I'm also hitting this same warning when building the documentation of the the nbsphinx repo. After cloning and installing dependencies, I run sphinx-build -b html doc doc/html whilc checked out to version 0.2.8.

The fix proposed by @ostrokach :

I had to add 'IPython.sphinxext.ipython_console_highlighting' to extensions in my conf.py.

also worked for me, warnings are gone.

Thanks!

[michaelaye]

The advise of

adding 'IPython.sphinxext.ipython_console_highlighting' to extensions in my conf.py

is not in the installation instructions yet, should it be added? I also receive this warning

/Users/klay6683/Dropbox/src/pyciss/docs/examples.ipynb:: WARNING: Pygments lexer name 'ipython3' is not known

multiple times for a single almost empty notebook and adding the above extension removed (masked?) that warning.

[mgeier]

@michaelaye If you get the warning even if you have the ipython package installed, this is IMHO a bug in its installation procedure. I'm re-opening this issue as a reminder.

Adding the IPython.sphinxext.ipython_console_highlighting extension is only a work-around, but not the real solution of the problem.

We can add a hint regarding the work-around to the docs (feel free to make a PR!), but it would be also very good to find the actual cause for the problem (and solve it).

[adrn]

I'm getting the same warnings. I set up a fresh conda environment, installed all packages as described in http://nbsphinx.readthedocs.io/en/0.2.12/usage.html

What do you mean by "a bug in its installation procedure"?

[mgeier]

What do you mean by "a bug in its installation procedure"?

expected behavior:

1. install the ipython package
2. the 'ipython3' lexer is available without additional actions to be taken

your observed behavior:

1. install ipython
2. the 'ipython3' lexer is not available

Therefore, I suspect there is a bug somewhere.
I don't know how the "registration" process of the lexer is supposed to work, but it definitely shows different behavior on different systems.

For me, on Linux/Debian shows the expected behavior.
It works also for the automatic build on readthedocs.

[mgeier]

So the reason might be a buggy Anaconda package: ContinuumIO/anaconda-issues#1430

[mgeier]

@adamjstewart

ipywidgets should only be required if there are widgets in the notebooks, more specifically, if there is some application/vnd.jupyter.widget-state+json data.

If you have widgets, you somehow have to provide the appropriate JavaScript files, which is done automatically if ipywidgets is available or manually with nbsphinx_widgets_path, see https://nbsphinx.readthedocs.io/en/0.8.9/code-cells.html#Interactive-Widgets-(HTML-only).

If none of your notebooks has any widgets but the warning is still shown, please let me know, because that may be a bug.

And yes, if you want to have code highlighting in code cells, you'll have to install IPython, see https://nbsphinx.readthedocs.io/en/0.8.9/installation.html#Pygments-Lexer-for-Syntax-Highlighting.

[Bilokin]

Hello, I have the same issue as @adamjstewart and my code highlight in the jupyter pages doesn't work and it broke a few days or weeks ago.
Example: https://syscorrfw.readthedocs.io/en/latest/particleid_weight_production.html
Is this issue already being worked on?
Which steps should I take to resolve it for my package?

[mgeier]

A new issue appeared very recently, see #687.