After installing the latest version of Python on Mac OS X using the installer downloaded from python.org (https://www.python.org/ftp/python/3.9.2/python-3.9.2-macosx10.9.pkg), the installed version of Python is unable to find the system certificates.

Using the old version of Python located at /usr/local/Cellar/python/3.7.5/bin/python3, I get:

>>> ssl.create_default_context().cert_store_stats()
{'x509': 168, 'crl': 0, 'x509_ca': 168}

But, with the new version located at /Library/Frameworks/Python.framework/Versions/3.9/bin/python3, I get:

>>> ssl.create_default_context().cert_store_stats()
{'x509': 0, 'crl': 0, 'x509_ca': 0}


Looking around on the internet, this seems to be a pretty common issue on Mac, but is often getting misdiagnosed as an actual problem with the server's certificate. Because of that, nobody seems to have proposed any methods to fix it.

Examples:
https://github.com/aio-libs/aiohttp/issues/5375
https://stackoverflow.com/questions/65039677/unable-to-get-local-issuer-certificate-mac-os#comment115039330_65040851