SSL: CERTIFICATE_VERIFY_FAILED error with python3 on macOS 10.15

The problem is that /usr/bin/python3 (from either Xcode or CLT) fails to correctly locate the trust store in /etc/ssl, as we can see using ssl.get_default_verify_paths():

$ /usr/bin/python3 -c 'import ssl; print(ssl.get_default_verify_paths())'
DefaultVerifyPaths(cafile=None, capath=None, openssl_cafile_env='SSL_CERT_FILE', openssl_cafile='/Applications/Xcode.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/etc/ssl/cert.pem', openssl_capath_env='SSL_CERT_DIR', openssl_capath='/Applications/Xcode.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/etc/ssl/certs')

It's looking into /Applications/Xcode.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/etc/ssl, which doesn't exist.

Knowing this, we can use the following hack:

$ sudo rsync -avzP /etc/ssl/ /Applications/Xcode.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/etc/ssl/

I've submitted a bug report to Apple (btw, just realized bugreport.apple.com is now gone, and I had to use the Feedback Assistant website). Open radar https://openradar.appspot.com/7111585 (that radar number is unfortunately wrong — since bugreport.apple.com is gone, I don't have a radar number anymore, only a feedback number FB7111585).

Supplemental to @4ae1e1's answer, you can create a symlink to the SSL folder instead of rsyncing it. This will give the added benefit of keeping any changes in /etc/ssl up-to-date at /Applications/Xcode.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/etc/ssl/.

/usr/bin/sudo /bin/mkdir /Applications/Xcode.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/etc
/usr/bin/sudo /bin/ln -s /etc/ssl/ /Applications/Xcode.app/Contents/Developer/Library/Frameworks/Python3.framework/Versions/3.7/etc/

Should do it.