Server extension doesn't seem to be loading (jlab 3.0)

Checklist prior to opening an issue

• I have followed fully the installation steps laid out in the documentation site.
• I have restarted jupyterlab.
• I have read the FAQ section in the documentation site.

Describe the bug The ser extension doesn’t seem to be loading in jupyter lab 3.0.

Diagnostic commands When I open jupyter lab in the browser I get the error message “Unable to find server plugin version, this should be impossible,open a GitHub issue if you cannot figure this issue out yourself.” In the terminal I see the following lines regarding the extension (with --debug):

[D 2021-01-02 14:47:45.920 ServerApp] Path @ryantam626/jupyterlab_code_formatter/static/remoteEntry.5c93eb886a3b8e74175b.js served from /home/darkxhunter/.local/share/jupyter/labextensions/@ryantam626/jupyterlab_code_formatter/static/remoteEntry.5c93eb886a3b8e74175b.js
[D 2021-01-02 14:47:45.921 ServerApp] 200 GET /lab/extensions/@ryantam626/jupyterlab_code_formatter/static/remoteEntry.5c93eb886a3b8e74175b.js (::1) 1.21ms
[D 2021-01-02 14:47:46.329 ServerApp] Path @ryantam626/jupyterlab_code_formatter/static/160.8feff4fb8d6302eb02fa.js served from /home/darkxhunter/.local/share/jupyter/labextensions/@ryantam626/jupyterlab_code_formatter/static/160.8feff4fb8d6302eb02fa.js
[D 2021-01-02 14:47:46.329 ServerApp] 200 GET /lab/extensions/@ryantam626/jupyterlab_code_formatter/static/160.8feff4fb8d6302eb02fa.js (::1) 0.85ms
[W 2021-01-02 14:47:48.916 ServerApp] 404 GET /jupyterlab_code_formatter/version?1609609668137 (::1) 615.31ms referer=http://localhost:8888/lab

• pip freeze | grep jupyter

jupyter-client==6.1.7
jupyter-console==6.2.0
jupyter-core==4.7.0
jupyter-server==1.1.3
jupyterlab==3.0.0
jupyterlab-code-formatter==1.4.1
jupyterlab-pygments==0.1.2
jupyterlab-server==2.0.0

• jupyter labextension list

JupyterLab v3.0.0
/home/darkxhunter/.local/share/jupyter/labextensions
        @ryantam626/jupyterlab_code_formatter v1.4.1 enabled OK (python, jupyterlab-code-formatter)

• jupyter serverextension list

config dir: /home/darkxhunter/.jupyter
    jupyterlab_code_formatter  enabled 
    - Validating...
      X is jupyterlab_code_formatter importable?

Additional context I’m using everything from user directory, not a virtualenv. Python 3.9 in OpenSUSE Tumbleweed. I also completely cleaned the jupyter installation (removing ~/.jupyter, ~/.local/share/jupyter and ~/.local/etc/jupyter, then reinstalling again jupyter and the extension), obtaining the same result.

Any ideas? Thanks!

[dialvarezs]

I was able to getting it work finally! With jupyterlab 3, the command to enable the extension is

jupyter server extension enable jupyterlab_code_formatter

With the space between “server” and “extension”. Using serverextension enables the extension using the “old” way (creating jupyter_notebook_config.json), with the new one a json file is added to jupyter_server_config.d (link). In my case was neccesary to add the --user option. A tricky one…

Executing jupyter server extension list, the output is

Config dir: /home/darkxhunter/.jupyter
    jupyterlab_code_formatter enabled
    - Validating jupyterlab_code_formatter...
      jupyterlab_code_formatter 1.4.1 OK

Config dir: /usr/etc/jupyter

Config dir: /usr/local/etc/jupyter

And everything is working as expected.

I also noticed in the documentation that in __init__.py the function to make the extension discoverable should be called _jupyter_server_extension_points (link), but it seems to work with _paths for now, so it shouldn’t be a problem, specially if it breaks the instalation in jlab < 3.0.0.

[okkymabruri]

@dialvarezs Thanks jupyter server extension enable jupyterlab_code_formatter --user also work for me