Jupyter notebook download as pdf: nbconvert failed: Pandoc wasn't found. nbconvert failed: No suitable chromium executable found on the system. Please use '--allow-chromium-download' to allow downloading one.

Install Pandoc

After that you need to have XeTex installed on your machine:

• Linux : TeX Live
• Mac : MacTex
• Windows : MikTex

Install nbconvert and pyppeteer

pip install nbconvert
pip install pyppeteer

Now we can convert an ipynb file to to PDF via HTML or via Tex.

jupyter nbconvert --to webpdf --allow-chromium-download filename.ipynb

or 

jupyter nbconvert --to pdf filename.ipynb

filename.ipynb is the filename of your file to be converted to a PDF file.