How to fix ModuleNotFoundError: No module named 'openpyxl'

ModuleNotFoundError: No module named 'openpyxl'
Recommended: Install via pip into your active environment.
python -m pip install openpyxl

Verification

Command
python -c "import openpyxl; print(openpyxl.__version__)"
Expected output
Success! openpyxl version x.y.z (e.g., 2.4.0)