zsh: command not found: jupyter

If zsh cannot find jupyter, use the Python interpreter that owns the environment instead of guessing which global installation is active.

command -v python
python --version
python -m jupyter --version

If the last command says the module is missing, activate the project's virtual environment and install the interface there:

source .venv/bin/activate
python -m pip install jupyterlab
python -m jupyter lab

On systems where python is not the Python 3 command, use python3 -m .... Conda users should activate the intended environment before running jupyter lab. Calling Jupyter through python -m jupyter avoids a common PATH mismatch between pip and jupyter.

If jupyter works only after opening a new terminal, the environment's bin directory was not active in the old shell. Avoid installing every notebook package globally; separate environments make project dependencies easier to reproduce.

Sources

• Project Jupyter — install

• Python Packaging User Guide