404 GET nbextensions/widgets/notebook/js/extension.js every time I open a notebook

[dburkhardt]

I'm not sure when this started or if it's really a problem, but every time I open a notebook I encounter the following warning:

[W 09:34:54.718 NotebookApp] 404 GET /jupyter/nbextensions/widgets/notebook/js/extension.js?v=20170627221437 (0.0.0.0) 1.47ms referer=</path/to/notebook.ipynb?kernel_name=python3

Any idea what this could be from? I can't find an extension.js file anywhere in my home directory.

I've seen this error in other issue posts before, but they all seem to have catastrophic errors that prevent Jupyter from running (dependencies, paths, etc.) but I don't. In fact, I'm even using a notebook extension without problem.

[takluyver]

Not a problem unless you're trying to use widgets. It may be listed in ~/.jupyter/nbconfig/notebook.json, or it may be something embedded in the notebooks you're opening that tries to load it.

[takluyver]

Here's info on how to install widgets if you do want to use them:
https://ipywidgets.readthedocs.io/en/latest/user_install.html

[nunocalaim]

I did a clean conda install, jupyter, and ipywidgets and I get the same error 404 GET /nbextensions/widgets/notebook/js/extension.js?v=20170922144630 (::1) 6.96ms

[demotu]

I had the same problem; although I installed ipywidgets (v. 7.0.5) with conda:
conda install -c conda-forge ipywidgets
it didn't appear as a nbextension when I executed in the terminal:
jupyter nbextension list
What solved my problem was to manually enable the widget in the terminal (although the docs say we don't need to do that):
jupyter nbextension enable --py widgetsnbextension
Then the widget appears in the list after the command in the terminal:
jupyter nbextension list
and as validated, look for the lines:
jupyter-js-widgets/extension enabled - Validating: ok

[mhogg]

After installing via conda, I also had to run:
jupyter nbextension enable --py widgetsnbextension

[joshmangum]

Same experience as mhogg and demotu. Installed via conda:
conda install -c conda-forge ipywidgets

But widget didn't load and got this on jupyter startup:
404 GET /nbextensions/widgets/notebook/js/extension.js

And this fixed it:
jupyter nbextension enable --py widgetsnbextension

This is on MacOS 10.13.1

[Rockbaron]

I had the same problem: "Run all cells above" did not execute any more properly. I do not know, when exactly this emerged. But, installing latest kernel and enabling widgets cleared the problem. Thanks!

[stas00]

same here: notebooks won't run on 'jupyter notebook' restart, running:

jupyter nbextension disable --py widgetsnbextension
jupyter nbextension enable --py widgetsnbextension

fixed it.

Note that it was already enabled and valid:

> jupyter nbextension disable --py widgetsnbextension
Disabling notebook extension jupyter-js-widgets/extension...
      - Validating: OK
> jupyter nbextension enable --py widgetsnbextension 
Enabling notebook extension jupyter-js-widgets/extension...
      - Validating: OK

i.e. you have a bug somewhere, as disabling/re-enabling it fixed it.

The 2 not OK configs were:

jupyter nbextension list
[...]
  config dir: /home/stas/.jupyter/nbconfig
    tree section
      nbextensions_configurator/tree_tab/main  enabled 
      - Validating: problems found:
        - require?  X nbextensions_configurator/tree_tab/main
  config dir: /usr/local/etc/jupyter/nbconfig
    notebook section
      nbdime/extension  enabled 
      - Validating: problems found:
        - require?  X nbdime/extension

Thank you!

[stas00]

Another update. The issues re-appeared after updating to notebook-5.6. I again started getting:

404 GET /nbextensions/widgets/notebook/js/extension.js?v=20180720194308

(same for nbdime)

which prevented notebooks restart and normal functioning. The disable-enable cycle didn't work this time.

After disabling and uninstalling ipywidgets system-wide and in the virtual env I was still getting jupyter-js-widgets/extension listed in the output of jupyter nbextension list, so it wasn't getting cleaned up.

I had to go and manually remove all remaining references to jupyter-js-widgets/extension in configuration files system-wide, under ~/.jupyter and in the virtual env. Eventually, jupyter nbextension list no longer listed jupyter-js-widgets/extension.

Only then reinstalling the python ipywidgets package and re-enabling widgetsnbextension and restarting the notebook got this resolved.

I had to do the same for nbdime extension.

[tc427]

Hello, I had the same issue, and solved it with:
jupyter nbextension install --py widgetsnbextension --user
found via: jupyter-widgets/ipywidgets#1720