[kadabra9]

I used to do a lot of work in Rails in around 2012-2014. Around 2015 or so I sort of pivoted out of web development and more into data engineering, so I took a bit of a hiatus from making side projects/web apps. When I revisited Rails years later, it seemed like so much had changed with all of the new versions and updates that it seemed like overkill, I just shrugged and ended up using Sinatra instead.

Is there a good resource out there for someone who used Rails 2.x / 3 a lot years ago to get caught up to speed on what they need to know to get up and running with the new(er) versions?

[xenorplxx]

You can definitely check out https://github.blog/2018-09-28-upgrading-github-from-rails-3... and other stories of big Rails upgrade to get a grasp of what has changed. As for new features, I'd just go with googling what's new in Rails 4/5.

[xenorplxx]

Oh, I've just noticed there's similar blog post on GitLab's blog now: https://about.gitlab.com/2019/05/28/upgrade-to-rails5/

[faizshah]

I've been using Hartl's Ruby on Rails Tutorial and Agile Web Development with Rails 5 by Sam Ruby. I had much less experience with Rails 3 than you so you might find it redundant but those have been the two best for me.