Jupyterlab Code Formatter Error Unable to find server plugin version

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 After JupyterLab server start, opening a client yields the following popup:

Jupyterlab Code Formatter Error
Unable to find server plugin version, this should be impossible, open a GitHub issue if you cannot figure this issue out yourself.

Diagnostic commands Please attach the output of the following commands (please format them properly)

• pip freeze

anyio==2.0.2
appdirs==1.4.4
argon2-cffi==20.1.0
arviz==0.10.0
astroid==2.4.2
async-generator==1.10
atomicwrites==1.1.5
attrs==20.3.0
Automat==20.2.0
autopep8==1.5.4
Babel==2.9.0
backcall==0.2.0
beautifulsoup4==4.9.3
black==20.8b1
bleach==3.2.1
blinker==1.4
boto==2.49.0
certifi==2020.12.5
cffi==1.14.4
cftime==1.3.0
chardet==4.0.0
click==7.1.2
cloud-init==20.4
colorama==0.4.4
command-not-found==0.3
configobj==5.0.6
constantly==15.1.0
cryptography==3.3.1
cssselect==1.1.0
cupshelpers==1.0
cvxopt==1.2.3
cycler==0.10.0
dbus-python==1.2.16
decorator==4.4.2
defer==1.0.6
defusedxml==0.6.0
dill==0.3.3
distro==1.5.0
distro-info===0.23ubuntu1
entrypoints==0.3
et-xmlfile==1.0.1
fastprogress==1.0.0
filelock==3.0.12
flake8==3.8.4
h5py==3.1.0
html5lib==1.1
httplib2==0.18.1
hyperlink==21.0.0
idna==2.10
importlib-metadata==3.4.0
incremental==17.5.0
ipykernel==5.4.3
ipympl==0.6.2
ipython==7.19.0
ipython-genutils==0.2.0
ipywidgets==7.6.3
isort==5.7.0
itemadapter==0.2.0
itemloaders==1.0.4
jdcal==1.0
jedi==0.17.2
jeepney==0.6.0
Jinja2==2.11.2
jmespath==0.10.0
joblib==0.14.0
json5==0.9.5
jsonpatch==1.28
jsonpointer==2.0
jsonschema==3.2.0
jupyter==1.0.0
jupyter-client==6.1.11
jupyter-console==6.2.0
jupyter-core==4.7.0
jupyter-resource-usage==0.5.1
jupyter-server==1.2.1
jupyterlab==3.0.4
jupyterlab-code-formatter==1.4.1
jupyterlab-pygments==0.1.2
jupyterlab-server==2.1.2
jupyterlab-widgets==1.0.0
keyring==21.8.0
kiwisolver==1.3.1
language-selector==0.1
launchpadlib==1.10.13
lazr.restfulclient==0.14.3
lazr.uri==1.0.5
lazy-object-proxy==1.4.3
llvmlite==0.31.0
lxml==4.6.2
macaroonbakery==1.3.1
MarkupSafe==1.1.1
matplotlib==3.3.3
mccabe==0.6.1
mistune==0.8.4
modbus-cli==0.1.3
more-itertools==8.6.0
mypy-extensions==0.4.3
mysqlclient==1.4.4
nbclassic==0.2.6
nbclient==0.5.1
nbconvert==6.0.7
nbformat==5.0.8
nest-asyncio==1.4.3
netCDF4==1.5.5.1
netifaces==0.10.9
nose==1.3.7
notebook==6.1.6
numba==0.48.0
numexpr==2.7.1
numpy==1.19.4
oauthlib==3.1.0
olefile==0.46
openpyxl==3.0.3
packaging==20.8
pandas==1.2.0
pandocfilters==1.4.3
parsel==1.6.0
parso==0.7.1
pathspec==0.8.1
patsy==0.5.1
pbr==5.5.1
pexpect==4.8.0
pickleshare==0.7.5
Pillow==8.1.0
pip-tools==5.5.0
pluggy==0.13.1
prometheus-client==0.9.0
prompt-toolkit==3.0.10
Protego==0.1.16
protobuf==3.14.0
psutil==5.8.0
ptyprocess==0.7.0
py==1.8.1
pyasn1==0.4.8
pyasn1-modules==0.2.8
pycairo==1.16.2
pycodestyle==2.6.0
pycparser==2.20
pycups==1.9.73
PyDispatcher==2.0.5
pydocstyle==5.1.1
pyflakes==2.2.0
pyftdi==0.52.9
Pygments==2.7.4
PyGObject==3.36.0
PyHamcrest==2.0.2
PyJWT==1.7.1
pylint==2.6.0
pymacaroons==0.13.0
pymc3==3.10.0
PyNaCl==1.4.0
pyOpenSSL==20.0.1
pyparsing==2.4.7
pyRFC3339==1.1
pyrsistent==0.17.3
pyserial==3.5
pytest==4.6.9
python-apt==2.0.0+ubuntu0.20.4.3
python-dateutil==2.8.1
python-debian==0.1.39
python-jsonrpc-server==0.4.0
python-language-server==0.36.2
pytz==2020.5
pyusb==1.1.0
PyYAML==5.3.1
pyzmq==20.0.0
qtconsole==5.0.1
QtPy==1.9.0
queuelib==1.5.0
regex==2020.11.13
requests==2.25.1
requests-unixsocket==0.2.0
rope==0.18.0
scikit-learn==0.22.2.post1
scipy==1.5.4
Scrapy==2.4.1
seaborn==0.11.1
SecretStorage==3.3.0
Send2Trash==1.5.0
service-identity==18.1.0
sidetable==0.8.0
simplejson==3.17.2
six==1.15.0
sklearn-pandas==1.8.0
sniffio==1.2.0
snowballstemmer==2.0.0
sos==4.0
soupsieve==2.1
ssh-import-id==5.11
statsmodels==0.11.1
systemd-python==234
tables==3.6.1
terminado==0.9.2
testpath==0.4.4
testresources==2.0.1
Theano==1.0.5
Theano-PyMC==1.1.0
toml==0.10.2
tornado==6.1
traitlets==5.0.5
Twisted==20.3.0
typed-ast==1.4.2
typing-extensions==3.7.4.3
ubuntu-advantage-tools==20.3
ufw==0.36
ujson==4.0.1
uModbus==1.0.4
unattended-upgrades==0.1
urllib3==1.26.2
w3lib==1.22.0
wadllib==1.3.4
wcwidth==0.2.5
webencodings==0.5.1
widgetsnbextension==3.5.1
wrapt==1.12.1
xarray==0.16.2
xlrd==1.1.0
xlwt==1.3.0
yapf==0.30.0
zipp==3.4.0
zope.interface==5.2.0

• jupyter labextension list

JupyterLab v3.0.4
/home/bobc/.local/share/jupyter/labextensions
        jupyter-matplotlib v0.8.2 enabled OK
        @jupyter-widgets/jupyterlab-manager v3.0.0 enabled OK (python, jupyterlab_widgets)
        @ryantam626/jupyterlab_code_formatter v1.4.1 enabled OK (python, jupyterlab-code-formatter)
        @jupyter-server/resource-usage v0.5.0 enabled OK (python, jupyter-resource-usage)

Other labextensions (built into JupyterLab)
   app dir: /home/bobc/.local/share/jupyter/lab
        @krassowski/jupyterlab-lsp v2.1.0 enabled OK

• jupyter serverextension list

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

Screenshots

Additional context

Running Python 3.8.5 under Ubuntu 20.04 under WSL2 under Windows 10. The rest is turtles all the way down.

[ryantam626]

Could you run jupyter server extension enable --py jupyterlab_code_formatter and retry?

I think this line was removed from the README by mistake.

[ast0815]

Thanks all! I just updated my pip install --user version of JupyterLab and had to set this in ~/.jupyter/jupyter_server_config.py:

c.ServerApp.jpserver_extensions = {
    "jupyterlab": True,
    "jupyterlab_code_formatter": True,
}

The ~/.jupyter/jupyter_server_config.py is necessary (and was not shown in the commented-out default value), because otherwise jupyter lab will not run at all.