Trying to start Jupyter Lab using jupyter lab gives the following error:
AttributeError: 'ExtensionManager' object has no attribute '_extensions'
In case this has anything to do with Python, I am using version 3.9.5 installed through Homebrew.
> which python3
python3: aliased to /usr/local/bin/python3
> python3 --version
Python 3.9.5
I installed Jupyter using pip3.
I am able to use jupyter notebook and jupyter console, however. Only jupyter lab results in this error message.
You can either update nbclassic as krassowski mentioned or disable the extension nbclassic until the bug is fixed.
In my case, updating nbclassic did not work on Apple M1. So, I had to disable it using -
jupyter server extension disable nbclassic
You need to upgrade nbclassic to the latest version:
pip install nbclassic==0.2.8 # in May 2021
pip install nbclassic -U # or just try this (may require running twice)
or if using conda:
conda install -c conda-forge nbclassic=0.2.8 # in May 2021
conda update nbclassic
This is because of changes introduced in jupyter-server release two days ago (2021-05-10), see the discussion in JupyterLab GitHub repo.
I also had the same issue.
There are two solutions for this problem you can try anyone which works for you.
Disable the nbclassic
jupyter server extension disable nbclassic
or downgrade jupyter_server
# if you have installed jupyter with using pip
pip install -U "nbclassic>=0.2.8"
# if you have got jupyter by anaconda
conda install "nbclassic>=0.2.8"
Personally, the first solution worked for me.