Rails 8.1.2 (January 08, 2026)

• Make delegate and delegate_missing_to work in BasicObject subclasses.

  Rafael Mendonça França

• Fix Inflectors when using a locale that fallbacks to :en.

  Said Kaldybaev

• Fix ActiveSupport::TimeWithZone#as_json to consistently return UTF-8 strings.

  Previously the returned string would sometime be encoded in US-ASCII, which in some cases may be problematic.

  Now the method consistently always return UTF-8 strings.

  Jean Boussier

• Fix TimeWithZone#xmlschema when wrapping a DateTime instance in local time.

  Previously it would return an invalid time.

  Dmytro Rymar

• Implement LocalCache strategy on ::ActiveSupport::Cache::MemoryStore. The memory store needs to respond to the same interface as other cache stores (e.g. ActiveSupport::NullStore).

  Mikey Gough

• Fix ActiveSupport::Inflector#humanize with international characters.

  ActiveSupport::Inflector.humanize("áÉÍÓÚ")  # => "Áéíóú"
  ActiveSupport::Inflector.humanize("аБВГДЕ") # => "Абвгде"

  Jose Luis Duran

Rails 8.1.1 (October 28, 2025)

• No changes.

Rails 8.1.0 (October 22, 2025)

• Remove deprecated passing a Time object to Time#since.

  Rafael Mendonça França

• Remove deprecated Benchmark.ms method. It is now defined in the benchmark gem.

  Rafael Mendonça França

• Remove deprecated addition for Time instances with ::ActiveSupport::TimeWithZone.

  Rafael Mendonça França

• Remove deprecated support for to_time to preserve the system local time. It will now always preserve the receiver timezone.

  Rafael Mendonça França

• Deprecate config.active_support.to_time_preserves_timezone.

  Rafael Mendonça França

• Standardize event name formatting in assert_event_reported error messages.

  The event name in failure messages now uses .inspect (e.g., name: "user.created") to match assert_events_reported and provide type clarity between strings and symbols. This only affects tests that assert on the failure message format itself.

  George Ma

• Fix Enumerable#sole to return the full tuple instead of just the first element of the tuple.

  Olivier Bellone

• Fix parallel tests hanging when worker processes die abruptly.

  Previously, if a worker process was killed (e.g., OOM killed, kill -9) during parallel test execution, the test suite would hang forever waiting for the dead worker.

  Joshua Young

• Add config.active_support.escape_js_separators_in_json.

  Introduce a new framework default to skip escaping LINE SEPARATOR (U+2028) and PARAGRAPH SEPARATOR (U+2029) in JSON.

  Historically these characters were not valid inside JavaScript literal strings but that changed in ECMAScript 2019. As such it's no longer a concern in modern browsers: https://caniuse.com/mdn-javascript_builtins_json_json_superset.

  Étienne Barrié, Jean Boussier

• Fix NameError when class_attribute is defined on instance singleton classes.

  Previously, calling class_attribute on an instance's singleton class would raise a NameError when accessing the attribute through the instance.

  object = MyClass.new
  object.singleton_class.class_attribute :foo, default: "bar"
  object.foo # previously raised NameError, now returns "bar"

  Joshua Young

• Introduce ActiveSupport::Testing::EventReporterAssertions#with_debug_event_reporting to enable event reporter debug mode in tests.

  The previous way to enable debug mode is by using #with_debug on the event reporter itself, which is too verbose. This new helper will help clear up any confusion on how to test debug events.

  Gannon McGibbon

• Add ::ActiveSupport::StructuredEventSubscriber for consuming notifications and emitting structured event logs. Events may be emitted with the #emit_event or #emit_debug_event methods.

  class MyStructuredEventSubscriber < ActiveSupport::StructuredEventSubscriber
    def notification(event)
      emit_event("my.notification", data: 1)
    end
  end

  Adrianna Chang

• ::ActiveSupport::FileUpdateChecker does not depend on Time.now to prevent unecessary reloads with time travel test helpers

  Jan Grodowski

• Add ActiveSupport::Cache::Store#namespace= and #namespace.

  Can be used as an alternative to Store#clear in some situations such as parallel testing.

  Nick Schwaderer

• Create parallel_worker_id helper for running parallel tests. This allows users to know which worker they are currently running in.

  Nick Schwaderer

• Make the cache of ::ActiveSupport::Cache::Strategy::LocalCache::Middleware updatable.

  If the cache client at Rails.cache of a booted application changes, the corresponding mounted middleware needs to update in order for request-local caches to be setup properly. Otherwise, redundant cache operations will erroneously hit the datastore.

  Gannon McGibbon

• Add assert_events_reported test helper for ::ActiveSupport::EventReporter.

  This new assertion allows testing multiple events in a single block, regardless of order:

  assert_events_reported([
    { name: "user.created", payload: { id: 123 } },
    { name: "email.sent", payload: { to: "user@example.com" } }
  ]) do
    create_user_and_send_welcome_email
  end

  George Ma

• Add ActiveSupport::TimeZone#standard_name method.

  zone = ActiveSupport::TimeZone['Hawaii']
  # Old way
  ActiveSupport::TimeZone::MAPPING[zone.name]
  # New way
  zone.standard_name # => 'Pacific/Honolulu'

  Bogdan Gusiev

• Add Structured Event Reporter, accessible via Rails.event.

  The Event Reporter provides a unified interface for producing structured events in Rails applications:

  Rails.event.notify("user.signup", user_id: 123, email: "user@example.com")

  It supports adding tags to events:

  Rails.event.tagged("graphql") do
    # Event includes tags: { graphql: true }
    Rails.event.notify("user.signup", user_id: 123, email: "user@example.com")
  end

  As well as context:

  # All events will contain context: {request_id: "abc123", shop_id: 456}
  Rails.event.set_context(request_id: "abc123", shop_id: 456)

  Events are emitted to subscribers. Applications register subscribers to control how events are serialized and emitted. Subscribers must implement an #emit method, which receives the event hash:

  class LogSubscriber
    def emit(event)
      payload = event[:payload].map { |key, value| "#{key}=#{value}" }.join(" ")
      source_location = event[:source_location]
      log = "[#{event[:name]}] #{payload} at #{source_location[:filepath]}:#{source_location[:lineno]}"
      Rails.logger.info(log)
    end
  end

  Adrianna Chang

• Make ::ActiveSupport::Logger #freeze-friendly.

  Joshua Young

• Make ActiveSupport::Gzip.compress deterministic based on input.

  ActiveSupport::Gzip.compress used to include a timestamp in the output, causing consecutive calls with the same input data to have different output if called during different seconds. It now always sets the timestamp to 0 so that the output is identical for any given input.

  Rob Brackett

• Given an array of ::Thread::Backtrace::Location objects, the new method ActiveSupport::BacktraceCleaner#clean_locations returns an array with the clean ones:

  clean_locations = backtrace_cleaner.clean_locations(caller_locations)

  Filters and silencers receive strings as usual. However, the path attributes of the locations in the returned array are the original, unfiltered ones, since locations are immutable.

  Xavier Noria

• Improve CurrentAttributes and ExecutionContext state managment in test cases.

  Previously these two global state would be entirely cleared out whenever calling into code that is wrapped by the Rails executor, typically Action Controller or Active Job helpers:

  test "#index works" do
    CurrentUser.id = 42
    get :index
    CurrentUser.id == nil
  end

  Now re-entering the executor properly save and restore that state.

  Jean Boussier

• The new method ActiveSupport::BacktraceCleaner#first_clean_location returns the first clean location of the caller's call stack, or nil. Locations are ::Thread::Backtrace::Location objects. Useful when you want to report the application-level location where something happened as an object.

  Xavier Noria

• FileUpdateChecker and EventedFileUpdateChecker ignore changes in Gem.path now.

  Ermolaev Andrey, zzak

• The new method ActiveSupport::BacktraceCleaner#first_clean_frame returns the first clean frame of the caller's backtrace, or nil. Useful when you want to report the application-level frame where something happened as a string.

  Xavier Noria

• Always clear CurrentAttributes instances.

  Previously CurrentAttributes instance would be reset at the end of requests. Meaning its attributes would be re-initialized.

  This is problematic because it assume these objects don't hold any state other than their declared attribute, which isn't always the case, and can lead to state leak across request.

  Now CurrentAttributes instances are abandoned at the end of a request, and a new instance is created at the start of the next request.

  Jean Boussier, Janko Marohnić

• Add public API for before_fork_hook in parallel testing.

  Introduces a public API for calling the before fork hooks implemented by parallel testing.

  parallelize_before_fork do
      # perform an action before test processes are forked
  end

  Eileen M. Uchitelle

• Implement ability to skip creating parallel testing databases.

  With parallel testing, Rails will create a database per process. If this isn't desirable or you would like to implement databases handling on your own, you can now turn off this default behavior.

  To skip creating a database per process, you can change it via the parallelize method:

  parallelize(workers: 10, parallelize_databases: false)

  or via the application configuration:

  config.active_support.parallelize_databases = false

  Eileen M. Uchitelle

• Allow to configure maximum cache key sizes

  When the key exceeds the configured limit (250 bytes by default), it will be truncated and the digest of the rest of the key appended to it.

  Note that previously ::ActiveSupport::Cache::RedisCacheStore allowed up to 1kb cache keys before truncation, which is now reduced to 250 bytes.

  config.cache_store = :redis_cache_store, { max_key_size: 64 }

  fatkodima

• Use UNLINK command instead of DEL in ::ActiveSupport::Cache::RedisCacheStore for non-blocking deletion.

  Aron Roh

• Add Cache#read_counter and Cache#write_counter

  Rails.cache.write_counter("foo", 1)
  Rails.cache.read_counter("foo") # => 1
  Rails.cache.increment("foo")
  Rails.cache.read_counter("foo") # => 2

  Alex Ghiculescu

• Introduce ActiveSupport::Testing::ErrorReporterAssertions#capture_error_reports

  Captures all reported errors from within the block that match the given error class.

  reports = capture_error_reports(IOError) do
    Rails.error.report(IOError.new("Oops"))
    Rails.error.report(IOError.new("Oh no"))
    Rails.error.report(StandardError.new)
  end
  
  assert_equal 2, reports.size
  assert_equal "Oops", reports.first.error.message
  assert_equal "Oh no", reports.last.error.message

  Andrew Novoselac

• Introduce ActiveSupport::ErrorReporter#add_middleware

  When reporting an error, the error context middleware will be called with the reported error and base execution context. The stack may mutate the context hash. The mutated context will then be passed to error subscribers. Middleware receives the same parameters as ErrorReporter#report.

  Andrew Novoselac, Sam Schmidt

• Change execution wrapping to report all exceptions, including Exception.

  If a more serious error like SystemStackError or NoMemoryError happens, the error reporter should be able to report these kinds of exceptions.

  Gannon McGibbon

• ActiveSupport::Testing::Parallelization.before_fork_hook allows declaration of callbacks that are invoked immediately before forking test workers.

  Mike Dalessio

• Allow the #freeze_time testing helper to accept a date or time argument.

  Time.current # => Sun, 09 Jul 2024 15:34:49 EST -05:00
  freeze_time Time.current + 1.day
  sleep 1
  Time.current # => Mon, 10 Jul 2024 15:34:49 EST -05:00

  Joshua Young

• ::ActiveSupport::JSON now accepts options

  It is now possible to pass options to ::ActiveSupport::JSON:

  ActiveSupport::JSON.decode('{"key": "value"}', symbolize_names: true) # => { key: "value" }

  matthaigh27

• ::ActiveSupport::Testing::NotificationAssertions's assert_notification now matches against payload subsets by default.

  Previously the following assertion would fail due to excess key vals in the notification payload. Now with payload subset matching, it will pass.

  assert_notification("post.submitted", title: "Cool Post") do
    ActiveSupport::Notifications.instrument("post.submitted", title: "Cool Post", body: "Cool Body")
  end

  Additionally, you can now persist a matched notification for more customized assertions.

  notification = assert_notification("post.submitted", title: "Cool Post") do
    ActiveSupport::Notifications.instrument("post.submitted", title: "Cool Post", body: Body.new("Cool Body"))
  end
  
  assert_instance_of(Body, notification.payload[:body])

  Nicholas La Roux

• Deprecate String#mb_chars and ::ActiveSupport::Multibyte::Chars.

  These APIs are a relic of the Ruby 1.8 days when Ruby strings weren't encoding aware. There is no legitimate reasons to need these APIs today.

  Jean Boussier

• Deprecate ::ActiveSupport::Configurable

  Sean Doyle

• nil.to_query("key") now returns key.

  Previously it would return key=, preventing round tripping with Rack::Utils.parse_nested_query.

  Erol Fornoles

• Avoid wrapping redis in a ConnectionPool when using ::ActiveSupport::Cache::RedisCacheStore if the :redis option is already a ConnectionPool.

  Joshua Young

• Alter ERB::Util.tokenize to return :PLAIN token with full input string when string doesn't contain ERB tags.

  Martin Emde

• Fix a bug in ERB::Util.tokenize that causes incorrect tokenization when ERB tags are preceded by multibyte characters.

  Martin Emde

• Add ::ActiveSupport::Testing::NotificationAssertions module to help with testing ::ActiveSupport::Notifications.

  Nicholas La Roux, Yishu See, Sean Doyle

• ActiveSupport::CurrentAttributes#attributes now will return a new hash object on each call.

  Previously, the same hash object was returned each time that method was called.

  fatkodima

• ActiveSupport::JSON.encode supports CIDR notation.

  Previously:

  ActiveSupport::JSON.encode(IPAddr.new("172.16.0.0/24")) # => "\"172.16.0.0\""

  After this change:

  ActiveSupport::JSON.encode(IPAddr.new("172.16.0.0/24")) # => "\"172.16.0.0/24\""

  Taketo Takashima

• Make ::ActiveSupport::FileUpdateChecker faster when checking many file-extensions.

  Jonathan del Strother

Please check [8-0-stable]) for previous changes.