matplotlib font not found

When you add new fonts to your system, you need to delete your fontList.cache file in order for matplotlib to find them.

The file fontList.cache is located at your Userfolder –> .matplotlib/fontList.cache or ~/.cache/matplotlib/fontList.cache, for Windows that would normally be C:\Users\yourUsername\.matplotlib\fontList.cache

matplotlib.font_manager
matplotlib.font_manager._rebuild()

References
https://stackoverflow.com/questions/26085867/matplotlib-font-not-found
http://andresabino.com/2015/08/18/fonts-and-matplotlib/
https://stackoverflow.com/questions/45877746/changing-fonts-in-matplotlib