It’s really best to keep your apps up to date with the latest minor version of Rails. But since that doesn’t always happen, you might find yourself needing to update. When I’m updating minor versions, I’m often curious to know what changed. Release Notes are not published on the blog for every minor release, but fortunately, the Rails team does a great job of recording notable changes into the CHANGELOG files.

For ease of browsing, here are links to all the CHANGELOGs for the past few versions of Rails.

Rails 4.0 (unreleased as of January 2013)

• actionmailer 4.0 CHANGELOG
• actionpack 4.0 CHANGELOG
• activemodel 4.0 CHANGELOG
• activerecord 4.0 CHANGELOG
• activesupport 4.0 CHANGELOG
• railties 4.0 CHANGELOG

Rails 3.2

Rails 3.2 Release Notes

• actionmailer 3.2 CHANGELOG
• actionpack 3.2 CHANGELOG
• activemodel 3.2 CHANGELOG
• activerecord 3.2 CHANGELOG
• activesupport 3.2 CHANGELOG
• railties 3.2 CHANGELOG

Rails 3.1

Rails 3.1 Release Notes

• actionmailer 3.1 CHANGELOG
• actionpack 3.1 CHANGELOG
• activemodel 3.1 CHANGELOG
• activerecord 3.1 CHANGELOG
• activesupport 3.1 CHANGELOG
• railties 3.1 CHANGELOG

Rails 3.0

Rails 3.0 Release Notes

(These CHANGELOG files are plain text)

• actionmailer 3.0 CHANGELOG
• actionpack 3.0 CHANGELOG
• activemodel 3.0 CHANGELOG
• activerecord 3.0 CHANGELOG
• activesupport 3.0 CHANGELOG
• railties 3.0 CHANGELOG

Rails 2.3

Rails 2.3 Release Notes

(These CHANGELOG files are plain text)

• actionmailer 2.3 CHANGELOG
• actionpack 2.3 CHANGELOG
• activerecord 2.3 CHANGELOG
• activeresource 2.3 CHANGELOG
• activesupport 2.3 CHANGELOG
• railties 2.3 CHANGELOG

Another, more low-level way to see changes between versions is to use the github compare view. For example, construct a url like the following:

https://github.com/rails/rails/compare/v3.2.9…v3.2.10

To see all the commits between two versions.