Installing OpenSSL 1.0.2t (or any older version) on MacOS 11.1 Big Sur using Homebrew

Go to Homebrew dir:

cd /usr/local/Homebrew/

Checkout Brew version that will allow git install:

git checkout 2.3.0

Fix "Version value must be a string; got a NilClass () (TypeError)"

THIS IS ONE COMMAND WITH LINE BREAKS:

sed -i '' '367a\
\ \ \ \ val = '$(sw_vers -productVersion)'\
' Library/Homebrew/version.rb

Install OpenSSL 1.0.2t from GitHub (if you need to install a specific version, look here):

HOMEBREW_NO_AUTO_UPDATE=1 brew install https://raw.githubusercontent.com/Homebrew/homebrew-core/64555220bfbf4a25598523c2e4d3a232560eaad7/Formula/openssl.rb

(do brew switch openssl 1.0.2t here if you need to)

Back to current Homebrew version:

git checkout -f -