Zeitwerk is the code autoloader and reloader that was integrated with Rails 6. Beginning in Rails 7, it will be the only codeloader option. As a result, upgrading to Zeitwerk will be an important step in getting your application ready for the next version of Rails. In this article, we’ll talk about upgrading your Rails 6 application from classic to zeitwerk mode.

One of the steps we recommend taking when doing an upgrade for any Rails version is to dual boot the application with your current Rails version and your next rails version.

This is important because it allows you to quickly run the test suite for both versions, having dual booting available allows you to debug and also revert to your current version in a much simpler fashion.

However, sometimes changes that you make for the new version of Rails may not be compatible with your current version of Rails. This means that you will need to use a few different techniques to get both versions to be able to use the dual booting and run smoothly.

Welcome to our series of Rails upgrade miniguides. Here you’ll find links to all of the relevant posts to help with an upgrade.

Sometimes you will be caught between a rock and a hard place. For example: You really need to upgrade your Rails application because Heroku is discontinuing your stack in two weeks so you don’t have the time to write an entire test suite.

Sometimes the situation will be that your boss really needs you to upgrade Ruby or Rails to use a version that gets security updates and they won’t allow you to write tests beforehand.

This article will explain how to ship a Rails upgrade project without a test suite. If your application has no tests, you will learn how to upgrade without having to write tests first.

This article is part of our Upgrade Rails series. To see more of them, click here.

This article will cover the most important aspects that you need to know to prepare your Ruby on Rails application for working on an upgrade.

If you’re a developer you know the reasons why you should be using the latest Rails framework. You understand the implications of performance gains, dependency issues and unsupported versions.

But these big picture benefits get lost in translation when talking to non-technical executives. What they need to know is the business case for an upgrade, how the work will translate into increased revenue.

So, here is an article to use or forward to communicate why an upgrade should be a priority. We also wrote an article on the more technical reasons if you are interested.