How to solve "NoneType' object is not iterable" when import pymatgen

Hello,
Today, I pip install MP-api, then from pymatgen.ext.matproj import MPRester, error**“NoneType’ object is not iterable”**. Before the “pip install MP-api”, it could work, but now it can’t work. How to solve it? Thanks.

Hello,

I had a similar issue starting yesterday after I tried to setup the POTCAR. Have you found a solution?