Error with https://ucare.cs.uchicago.edu/pdf/eurosys19-flyMC.pdf

exception = HTTPSConnectionPool(host='ucare.cs.uchicago.edu', port=443): Max retries exceeded with url: /pdf/eurosys19-flyMC.pdf (Caused by SSLError(SSLCertVerificationError(1, '[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed: unable to get local issuer certificate (_ssl.c:992)')))