I had the same problem on Mac OS(Mojave) and solved the problem as mentioned on this link - Openssl issue.
If you do not have Homebrew or don't know what is Homebrew:
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
Or if you already have Homebrew installed:
brew update && brew upgrade
brew uninstall --ignore-dependencies openssl; brew install https://github.com/tebelorg/Tump/releases/download/v1.0.0/openssl.rb
Update:
Keep in mind, that I had to use --ignore-dependencies
flag, because other packages installed that depend on OpenSSL.
Additional if the problem is caused after using pyenv, you can fix it by using:
brew reinstall python