
Use bin/rails for running tasks and tests. Removed Support for Legacy mysql Database Adapter. Autoloading is Disabled After Booting in the Production Environment. ActiveJob Now Inherits from ApplicationJob by Default. Halting Callback Chains via throw(:abort). Active Record Models Now Inherit from ApplicationRecord by Default. Removed deprecated support of redirect_to :back. Removed deprecated support to :text and :nothing in render. crets now loaded with all keys as symbols. Top-level HashWithIndifferentAccess is soft-deprecated. Expiry in signed or encrypted cookie is now embedded in the cookies values. Active Storage assignment behavior change. ActionDispatch::Response#content_type now returns the Content-Type header without modification. All npm packages have been moved to the scope. Purpose and expiry metadata is now embedded inside signed and encrypted cookies for increased security. Active Storage now requires Image Processing. Redirection to HTTPS from HTTP will now use the 308 HTTP status code. The helper class method in controllers uses String#constantize. ActiveSupport::Callbacks#halted_callback_hook now receive a second argument. Response's Content-Type when using respond_to#any.
_for return value no longer supports access with String keys.Rails version is now included in the Active Record schema dump.Active Storage default variant processor changed to :vips.Active Storage video preview image generation.New ActiveSupport::Cache serialization format.Digest class for ActiveSupport::Digest changing to SHA256.Key generator digest class changing to use SHA256.ActionDispatch::Request#content_type now returns Content-Type header as it is.
Ability to configure toload_once_paths.ActiveSupport::Dependencies private API has been deleted.Applications need to run in zeitwerk mode.Sprockets is now an optional dependency.ActionView::Helpers::UrlHelper#button_to changed behavior.