In Ruby 2.3, if the argument to open-uri is http and the host redirects to https , then open-uri would throw an error.

> require 'open-uri' > open ( 'http://www.google.com/gmail' ) RuntimeError : redirection forbidden: http :/ / www . google . com / gmail -> https :/ / www . google . com / gmail /

To get around this issue, we could use open_uri_redirections gem.

> require 'open-uri' > require 'open_uri_redirections' > open ( 'http://www.google.com/gmail/' , :allow_redirections => :safe ) => #<Tempfile:/var/folders/jv/fxkfk9_10nb_964rvrszs2540000gn/T/open-uri20170228-41042-2fffoa>

Ruby 2.4

In Ruby 2.4, this issue is fixed. So now http to https redirection is possible using open-uri.

> require 'open-uri' > open ( 'http://www.google.com/gmail' ) => #<Tempfile:/var/folders/jv/fxkfk9_10nb_964rvrszs2540000gn/T/open-uri20170228-41077-1bkm1dv>

Note that redirection from https to http will raise an error, like it did in previous versions, since that has possible security concerns.