"ipcluster nbextension enable" doesn't have subcommand specified - ipython-parallel

Question

I have ipyparallel 5.3.0. Its official doc, https://github.com/ipython/ipyparallel#install, instructs the following:
To enable the IPython Clusters tab in Jupyter Notebook:
ipcluster nbextension enable
But I got the following issue hence it didn't work.
No subcommand specified. Must specify one of: ['start', 'stop', 'engines'].
I did more checks following minrk's tips.
$ipcluster --version
5.2.0
$which -a ipcluster
/home/etlolap/anaconda3/bin/ipcluster
/user/bin/cluster
$head -n 1 $(which ipcluster)
#!/home/etlolap/anaconda3/bin/python
Everything looks fine though.

Answer 1

For all users with root/admin access :
sudo jupyter serverextension enable --py ipyparallel
sudo jupyter nbextension install --py ipyparallel
sudo jupyter nbextension enable --py ipyparallel
Don't forget to start it by :
ipcluster start

Answer 2

That suggests that ipcluster doesn't point to the version you expect to have installed. What do you see for:
ipcluster --version
? You might also check if there's more than one installed with:
which -a ipcluster
You can also verify that the ipcluster command is started with the Python you expect with:
head -n 1 $(which ipcluster)
If there is some confusion of package versions, it can help to remove and reinstall the package. Repeat:
pip uninstall ipyparallel
Until it says there is no ipyparallel package found, then install again with:
pip install --upgrade ipyparallel

Answer 3

For anyone facing this issue, try on your terminal :
jupyter serverextension enable --py ipyparallel --user
jupyter nbextension install --py ipyparallel --user
jupyter nbextension enable --py ipyparallel --user
It worked just fine for me, I had the same command problem and everything seemed well installed (ipcluster version, python version...).
The issue was also debated on IPython's Github if you need further information : https://github.com/ipython/ipyparallel/issues/170