# Upgrading Rails 4.2 to Rails 8: Count Sites, Not Warnings

DevFeed: [Upgrading Rails 4.2 to Rails 8: Count Sites, Not Warnings](<https://devfeed.tech/articles/upgrading-rails-4-2-to-rails-8-count-sites-not-warnings-39663.md>)

Original publisher: [Read original article](<https://www.gauravsarma.com/posts/2026-08-08_upgrading-rails-4-to-rails-8>)

Published: 2026-08-08T00:00:00Z

Content type: tutorial

Language: en

Sources: [Gaurav Sarma's Blog](<https://devfeed.tech/sources/gaurav-sarma-s-blog.md>)

Topics: [Rails](<https://devfeed.tech/topics/rails.md>), [upgrade](<https://devfeed.tech/topics/upgrade.md>), [version](<https://devfeed.tech/topics/version.md>), [Test coverage](<https://devfeed.tech/topics/coverage.md>), [RSpec](<https://devfeed.tech/topics/rspec.md>), [Docker Compose](<https://devfeed.tech/topics/docker-compose.md>), [Ruby](<https://devfeed.tech/topics/ruby.md>)

Tags: [coverage](<https://devfeed.tech/tags/coverage.md>), [docker-compose](<https://devfeed.tech/tags/docker-compose.md>), [rails](<https://devfeed.tech/tags/rails.md>), [rspec](<https://devfeed.tech/tags/rspec.md>), [ruby](<https://devfeed.tech/tags/ruby.md>), [upgrade](<https://devfeed.tech/tags/upgrade.md>), [version](<https://devfeed.tech/tags/version.md>)

## AI overview

An account of upgrading a multi-tenant JSON API from Rails 4.2.7.1 to Rails 8. The author argues that estimates focused on version gates missed the actual risks, and describes how characterization tests, an extracted frontend, and containerized development reduced the work.

## Source excerpt

. [Upgrading Rails 4...