SSLError installing with pip

My pip was working fine (Windows 7 and Python 3.8.6) until I upgraded pip from version 20.2.1 to 20.3.1, after which I also got the error:

SSL: WRONG_VERSION_NUMBER error.

This is reproducible. I uninstalled and reinstalled several times to confirm.

Solution (well, workaround): don't upgrade pip to 20.3.1.

Note: pip 20.3.1 works fine in my Windows 7/Python 3.9.1 environment.

Setting up my proxy correctly fixed this for me as well. The problem was that I used the https protocol for my HTTPS_PROXY and https_proxy environment variables.

Use:

HTTPS_PROXY="http://username:[email protected]:8080"
https_proxy="http://username:[email protected]:8080"

Do not use:

HTTPS_PROXY="https://username:[email protected]:8080"
https_proxy="https://username:[email protected]:8080"