Each new version of Rails builds on the strengths of its predecessors and offers developers improved tools, higher performance and new features to create web applications more efficiently and effectively.

A Rails update to the latest version allows developers to benefit from these advances. In addition, for security reasons, at a certain point it is essential to either upgrade to a new version or to guarantee the security of the applications in some other way. 

Here you can find out everything about Rails 6, what EOL (End of Life) means in the Rails world and how you can protect your outdated Rails version today.

• Action Mailbox for incoming Eemails
  Action Mailbox allows routing incoming emails to controller-like mailboxes. This facilitates processing emails within the application, enabling features like creating support tickets or comments directly from emails.
• Action Text for rich text editing
  Action Text integrates rich text content editing directly into Rails. It includes the Trix editor, supporting formatting, links, quotes, lists, and embedding images and galleries. The created content is stored in its own RichText model and can be associated with Active Record models.
• Parallel testing for faster test execution
  Rails 6 introduces the ability to run test suites in parallel. By distributing tests across multiple processes or threads, the total time required for testing is significantly reduced, enhancing development efficiency.
• Multiple database support
  Rails 6 introduces native support for multiple databases. Developers can now more easily switch between different database connections and configure models to interact with various data sources. This is particularly useful for applications that utilize data from different sources or require a separation of read and write operations.
• Default integration of Webpacker
  Rails 6 sets Webpacker as the default for managing JavaScript. This facilitates the integration of modern JavaScript libraries and frameworks, promoting contemporary frontend development within Rails applications.
• New autoloader "Zeitwerk"
  Rails 6 introduces "Zeitwerk" as a new code loader. It is efficient, thread-safe, and aligns with Ruby's constant semantics. Zeitwerk automatically loads classes and modules on demand, reducing the need for manual require statements and improving code organization.

There are good reasons that prevent companies from updating to the latest version of Rails. Here are some challenges you might run into when planning your upgrade.

• Extensive gem upgrades are necessary
  Any gem that integrates with Rails needs to be updated to a newer version. Unmaintained gems must be replaced with a newer version.
• Monkey patches will break
  Any monkey patches that hook into the internals of Rails or other gems typically break with an upgrade.
• Upgrades can be hard to execute
  When a Rails application has poor test coverage, testing an update is challenging. In addition, all feature development must be paused during the upgrade.
• Secrets.yml is no longer supported
  Rails 7 has dropped support for secrets. Any secrets must be migrated to use encrypted credentials.
• New handling for frontend assets
  Rails has overhauled its asset pipeline three times—first moving to Sprockets, then to Webpacker, then to Propshaft with external build tools (like esbuild) for JavaScripts.
• API changes
  As the Rails API evolves with every major version, various classes, methods and options have been renamed or removed.
• Webpacker has been removed
  The Webpacker gem has been removed from Rails 7 and is no longer maintained. JavaScript files must be processed using import maps, esbuild oder another external build tool.