diff --git a/Gemfile b/Gemfile
index 9a0e1d6094..a294fb7206 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,7 +5,7 @@ ruby '>= 3.2.0', '< 3.5.0'
 
 gem 'propshaft'
 gem 'puma', '~> 7.0'
-gem 'rails', '~> 8.0'
+gem 'rails', '~> 8.1.0'
 gem 'thor', '~> 1.2'
 
 gem 'dotenv'
diff --git a/Gemfile.lock b/Gemfile.lock
index 8feb1490d0..d71fa8360c 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -10,29 +10,31 @@ GIT
 GEM
   remote: https://rubygems.org/
   specs:
-    actioncable (8.0.3)
-      actionpack (= 8.0.3)
-      activesupport (= 8.0.3)
+    action_text-trix (2.1.16)
+      railties
+    actioncable (8.1.2)
+      actionpack (= 8.1.2)
+      activesupport (= 8.1.2)
       nio4r (~> 2.0)
       websocket-driver (>= 0.6.1)
       zeitwerk (~> 2.6)
-    actionmailbox (8.0.3)
-      actionpack (= 8.0.3)
-      activejob (= 8.0.3)
-      activerecord (= 8.0.3)
-      activestorage (= 8.0.3)
-      activesupport (= 8.0.3)
+    actionmailbox (8.1.2)
+      actionpack (= 8.1.2)
+      activejob (= 8.1.2)
+      activerecord (= 8.1.2)
+      activestorage (= 8.1.2)
+      activesupport (= 8.1.2)
       mail (>= 2.8.0)
-    actionmailer (8.0.3)
-      actionpack (= 8.0.3)
-      actionview (= 8.0.3)
-      activejob (= 8.0.3)
-      activesupport (= 8.0.3)
+    actionmailer (8.1.2)
+      actionpack (= 8.1.2)
+      actionview (= 8.1.2)
+      activejob (= 8.1.2)
+      activesupport (= 8.1.2)
       mail (>= 2.8.0)
       rails-dom-testing (~> 2.2)
-    actionpack (8.0.3)
-      actionview (= 8.0.3)
-      activesupport (= 8.0.3)
+    actionpack (8.1.2)
+      actionview (= 8.1.2)
+      activesupport (= 8.1.2)
       nokogiri (>= 1.8.5)
       rack (>= 2.2.4)
       rack-session (>= 1.0.1)
@@ -40,15 +42,16 @@ GEM
       rails-dom-testing (~> 2.2)
       rails-html-sanitizer (~> 1.6)
       useragent (~> 0.16)
-    actiontext (8.0.3)
-      actionpack (= 8.0.3)
-      activerecord (= 8.0.3)
-      activestorage (= 8.0.3)
-      activesupport (= 8.0.3)
+    actiontext (8.1.2)
+      action_text-trix (~> 2.1.15)
+      actionpack (= 8.1.2)
+      activerecord (= 8.1.2)
+      activestorage (= 8.1.2)
+      activesupport (= 8.1.2)
       globalid (>= 0.6.0)
       nokogiri (>= 1.8.5)
-    actionview (8.0.3)
-      activesupport (= 8.0.3)
+    actionview (8.1.2)
+      activesupport (= 8.1.2)
       builder (~> 3.1)
       erubi (~> 1.11)
       rails-dom-testing (~> 2.2)
@@ -58,29 +61,29 @@ GEM
       activemodel (>= 4.1)
       case_transform (>= 0.2)
       jsonapi-renderer (>= 0.1.1.beta1, < 0.3)
-    activejob (8.0.3)
-      activesupport (= 8.0.3)
+    activejob (8.1.2)
+      activesupport (= 8.1.2)
       globalid (>= 0.3.6)
-    activemodel (8.0.3)
-      activesupport (= 8.0.3)
-    activerecord (8.0.3)
-      activemodel (= 8.0.3)
-      activesupport (= 8.0.3)
+    activemodel (8.1.2)
+      activesupport (= 8.1.2)
+    activerecord (8.1.2)
+      activemodel (= 8.1.2)
+      activesupport (= 8.1.2)
       timeout (>= 0.4.0)
-    activestorage (8.0.3)
-      actionpack (= 8.0.3)
-      activejob (= 8.0.3)
-      activerecord (= 8.0.3)
-      activesupport (= 8.0.3)
+    activestorage (8.1.2)
+      actionpack (= 8.1.2)
+      activejob (= 8.1.2)
+      activerecord (= 8.1.2)
+      activesupport (= 8.1.2)
       marcel (~> 1.0)
-    activesupport (8.0.3)
+    activesupport (8.1.2)
       base64
-      benchmark (>= 0.3)
       bigdecimal
       concurrent-ruby (~> 1.0, >= 1.3.1)
       connection_pool (>= 2.2.5)
       drb
       i18n (>= 1.6, < 2)
+      json
       logger (>= 1.4.2)
       minitest (>= 5.1)
       securerandom (>= 0.3)
@@ -657,20 +660,20 @@ GEM
       rack (>= 1.3)
     rackup (2.3.1)
       rack (>= 3)
-    rails (8.0.3)
-      actioncable (= 8.0.3)
-      actionmailbox (= 8.0.3)
-      actionmailer (= 8.0.3)
-      actionpack (= 8.0.3)
-      actiontext (= 8.0.3)
-      actionview (= 8.0.3)
-      activejob (= 8.0.3)
-      activemodel (= 8.0.3)
-      activerecord (= 8.0.3)
-      activestorage (= 8.0.3)
-      activesupport (= 8.0.3)
+    rails (8.1.2)
+      actioncable (= 8.1.2)
+      actionmailbox (= 8.1.2)
+      actionmailer (= 8.1.2)
+      actionpack (= 8.1.2)
+      actiontext (= 8.1.2)
+      actionview (= 8.1.2)
+      activejob (= 8.1.2)
+      activemodel (= 8.1.2)
+      activerecord (= 8.1.2)
+      activestorage (= 8.1.2)
+      activesupport (= 8.1.2)
       bundler (>= 1.15.0)
-      railties (= 8.0.3)
+      railties (= 8.1.2)
     rails-dom-testing (2.3.0)
       activesupport (>= 5.0.0)
       minitest
@@ -681,9 +684,9 @@ GEM
     rails-i18n (8.1.0)
       i18n (>= 0.7, < 2)
       railties (>= 8.0.0, < 9)
-    railties (8.0.3)
-      actionpack (= 8.0.3)
-      activesupport (= 8.0.3)
+    railties (8.1.2)
+      actionpack (= 8.1.2)
+      activesupport (= 8.1.2)
       irb (~> 1.13)
       rackup (>= 1.0.0)
       rake (>= 12.2)
@@ -1050,7 +1053,7 @@ DEPENDENCIES
   rack-attack (~> 6.6)
   rack-cors
   rack-test (~> 2.1)
-  rails (~> 8.0)
+  rails (~> 8.1.0)
   rails-i18n (~> 8.0)
   rdf-normalize (~> 0.5)
   redcarpet (~> 3.6)
diff --git a/app/lib/admin/metrics/measure/base_measure.rb b/app/lib/admin/metrics/measure/base_measure.rb
index eabbe0890b..88a7cb09a0 100644
--- a/app/lib/admin/metrics/measure/base_measure.rb
+++ b/app/lib/admin/metrics/measure/base_measure.rb
@@ -94,7 +94,7 @@ class Admin::Metrics::Measure::BaseMeasure
   end
 
   def length_of_period
-    @length_of_period ||= @end_at - @start_at
+    @length_of_period ||= @end_at.to_date - @start_at.to_date
   end
 
   def params
diff --git a/config/application.rb b/config/application.rb
index 4e58bd9f6c..09fe38065e 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -58,7 +58,7 @@ Bundler.require(:pam_authentication) if ENV['PAM_ENABLED'] == 'true'
 module Mastodon
   class Application < Rails::Application
     # Initialize configuration defaults for originally generated Rails version.
-    config.load_defaults 8.0
+    config.load_defaults 8.1
 
     # Please, add to the `ignore` list any other `lib` subdirectories that do
     # not contain `.rb` files, or that should not be reloaded or eager loaded.
diff --git a/config/environments/development.rb b/config/environments/development.rb
index 4f3e076e7c..1d9ba5a8fc 100644
--- a/config/environments/development.rb
+++ b/config/environments/development.rb
@@ -28,7 +28,7 @@ Rails.application.configure do
 
     config.cache_store = :redis_cache_store, REDIS_CONFIGURATION.cache
     config.public_file_server.headers = {
-      'Cache-Control' => "public, max-age=#{2.days.to_i}",
+      'cache-control' => "public, max-age=#{2.days.to_i}",
     }
   else
     config.action_controller.perform_caching = false
@@ -67,9 +67,18 @@ Rails.application.configure do
   # Highlight code that triggered database queries in logs.
   config.active_record.verbose_query_logs = true
 
+  # Append comments with runtime information tags to SQL queries in logs.
+  config.active_record.query_log_tags_enabled = true
+
   # Highlight code that enqueued background job in logs.
   config.active_job.verbose_enqueue_logs = true
 
+  # Highlight code that triggered redirect in logs.
+  config.action_dispatch.verbose_redirect_logs = true
+
+  # Suppress logger output for asset requests.
+  config.assets.quiet = true
+
   # Raises error for missing translations.
   # config.i18n.raise_on_missing_translations = true
 
diff --git a/config/environments/production.rb b/config/environments/production.rb
index 993e418691..5f655e01f1 100644
--- a/config/environments/production.rb
+++ b/config/environments/production.rb
@@ -11,8 +11,10 @@ Rails.application.configure do
   # Eager load code on boot for better performance and memory savings (ignored by Rake tasks).
   config.eager_load = true
 
-  # Full error reports are disabled and caching is turned on.
+  # Full error reports are disabled.
   config.consider_all_requests_local = false
+
+  # Turn on fragment caching in view templates.
   config.action_controller.perform_caching = true
 
   # Do not fallback to assets pipeline if a precompiled asset is missed.
@@ -55,9 +57,8 @@ Rails.application.configure do
   # Use a different cache store in production.
   config.cache_store = :redis_cache_store, REDIS_CONFIGURATION.cache
 
-  # Disable caching for Action Mailer templates even if Action Controller
-  # caching is enabled.
-  config.action_mailer.perform_caching = false
+  # Prevent health checks from clogging up the logs.
+  config.silence_healthcheck_path = '/health'
 
   # Don't log any deprecations.
   config.active_support.report_deprecations = false
@@ -104,6 +105,9 @@ Rails.application.configure do
     'Referrer-Policy' => 'same-origin',
   }
 
+  # Only use :id for inspections in production.
+  config.active_record.attributes_for_inspect = [:id]
+
   # Enable DNS rebinding protection and other `Host` header attacks.
   # config.hosts = [
   #   "example.com",     # Allow requests from example.com
diff --git a/config/initializers/open_redirects.rb b/config/initializers/open_redirects.rb
index 1c5a66e07d..821fde784d 100644
--- a/config/initializers/open_redirects.rb
+++ b/config/initializers/open_redirects.rb
@@ -1,7 +1,12 @@
 # frozen_string_literal: true
 
-# TODO: Starting with Rails 7.0, the framework default is true for this setting.
-# This location in devise redirects and we can't hook in or override:
-# https://github.com/heartcombo/devise/blob/v4.9.3/app/controllers/devise/confirmations_controller.rb#L28
-# When solution is found, this setting can go back to default.
-Rails.application.config.action_controller.raise_on_open_redirects = false
+# In the Devise confirmations#show action, a redirect_to is called:
+# https://github.com/heartcombo/devise/blob/v5.0.0/app/controllers/devise/confirmations_controller.rb#L28
+#
+# We override the `after_confirmation_path_for` method in a way which sometimes
+# returns raw URLs to external hosts, as part of the auth workflow.
+# Discussion: https://github.com/mastodon/mastodon/pull/36505#discussion_r2782876831
+
+Rails.application.reloader.to_prepare do
+  ActionController::Base.action_on_open_redirect = :log
+end
diff --git a/config/routes.rb b/config/routes.rb
index b516a48866..3ddd3494d3 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -12,7 +12,7 @@ class RedirectWithVary < ActionDispatch::Routing::PathRedirect
 end
 
 def redirect_with_vary(path)
-  RedirectWithVary.new(301, path)
+  RedirectWithVary.new(301, path, caller(1..1).first)
 end
 
 Rails.application.routes.draw do