I am trying to use the AWS IoT basicPubSub.py script to test my AWS connection, but I keep getting this error. I have tried various fixes, but cannot resolve the problem. 
I have tried it using my MacBook and RPi and still have the same issue.
ssl.SSLError: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:720)
I am not sure how I managed to fix this problem, I tried the following items to fix the problem:
Re-created all the certificates
Re-installated CLI using sudo
Installed ssl (sudo apt-get install -y libssl-dev)
I going to do a fresh installation on my RPi and repeat the steps to understand how this was resolved and fixed.
SSL error - certificate verify failed - AWS IOT (basicPubSub.py)