AssertionError: Couldn't find Class NSProcessInfo

Apparently this issue occurs only on Mac with Big Sur OS. This issue was filed for correction but you can work around it by installing the Jupyter Lab using pip instead of conda.

pip install jupyterlab

See this reference: https://github.com/jupyterlab/jupyterlab/issues/9410

If you use Conda environment, create with python 3.7 version at first. and install the jupyterlab with pip

(Example: "rdkit" environment)

 conda create -n rdkit python=3.7.9
 conda activate rdkit

 pip install jupyterlab

 # and then 
 jupyter lab --ip=0.0.0.0 --port=8800 --no-browser