diff --git a/app/lib/formatter.rb b/app/lib/formatter.rb
index 4ee3c234..21cd4f17 100644
--- a/app/lib/formatter.rb
+++ b/app/lib/formatter.rb
@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 require 'singleton'
-require_relative './sanitize_config'
+require_relative './sanitize/config'
 
 class HTMLRenderer < Redcarpet::Render::HTML
   def block_code(code, language)
diff --git a/app/lib/sanitize_config.rb b/app/lib/sanitize/config.rb
similarity index 100%
rename from app/lib/sanitize_config.rb
rename to app/lib/sanitize/config.rb
diff --git a/config/application.rb b/config/application.rb
index 906ce23c..1758473b 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -6,7 +6,7 @@ require 'rails/all'
 # you've limited to :test, :development, or :production.
 Bundler.require(*Rails.groups)
 
-require_relative '../app/lib/exceptions'
+require_relative '../lib/exceptions'
 require_relative '../lib/paperclip/lazy_thumbnail'
 require_relative '../lib/paperclip/gif_transcoder'
 require_relative '../lib/paperclip/video_transcoder'
@@ -23,7 +23,7 @@ require_relative '../lib/gabsocial/redis_config'
 module GabSocial
   class Application < Rails::Application
     # Initialize configuration defaults for originally generated Rails version.
-    config.load_defaults 5.2
+    config.load_defaults 6.0
 
     # Settings in config/environments/* take precedence over those specified here.
     # Application configuration should go into files in config/initializers
diff --git a/config/initializers/inflections.rb b/config/initializers/inflections.rb
index 6831bdb6..7b169a7e 100644
--- a/config/initializers/inflections.rb
+++ b/config/initializers/inflections.rb
@@ -10,7 +10,27 @@
 #   inflect.uncountable %w( fish sheep )
 # end
 
-# : TODO : WTF IS THIS?
+
+
+# When converting a file path to a constant name and vice versa, Rails uses inflections to know
+# what to do. It uses the `humanize` method to convert a path to a constant, and it uses
+# `underscore` to convert a constant to a path.
+#
+# The inflections below are ones that do not follow the typical convention of underscore/humanize.
+# Referring to it as an "acronym" is the easiest way to tell it, "this constant should just be
+# downcased to become a path".
+#
+# BEFORE:
+# 'StatsD'.underscore
+# => "stats_d"
+# 'statsd'.humanize
+# => "Statsd"
+#
+# AFTER: (inflect.acronym 'StatsD')
+# 'StatsD'.underscore
+# => "statsd"
+# 'statsd'.humanize
+# => "StatsD"
 ActiveSupport::Inflector.inflections(:en) do |inflect|
   inflect.acronym 'StatsD'
   inflect.acronym 'OEmbed'
@@ -19,4 +39,5 @@ ActiveSupport::Inflector.inflections(:en) do |inflect|
   inflect.acronym 'PubSubHubbub'
   inflect.acronym 'ActivityStreams'
   inflect.acronym 'JsonLd'
+  inflect.acronym 'REST'
 end
diff --git a/config/initializers/new_framework_defaults_6_0.rb b/config/initializers/new_framework_defaults_6_0.rb
deleted file mode 100644
index d45195a0..00000000
--- a/config/initializers/new_framework_defaults_6_0.rb
+++ /dev/null
@@ -1,53 +0,0 @@
-# Be sure to restart your server when you modify this file.
-#
-# This file contains migration options to ease your Rails 6.0 upgrade.
-#
-# Once upgraded flip defaults one by one to migrate to the new default.
-#
-# Read the Guide for Upgrading Ruby on Rails for more info on each option.
-
-# Don't force requests from old versions of IE to be UTF-8 encoded.
-Rails.application.config.action_view.default_enforce_utf8 = false
-
-# Embed purpose and expiry metadata inside signed and encrypted
-# cookies for increased security.
-#
-# This option is not backwards compatible with earlier Rails versions.
-# It's best enabled when your entire app is migrated and stable on 6.0.
-# Rails.application.config.action_dispatch.use_cookies_with_metadata = true
-
-# Change the return value of `ActionDispatch::Response#content_type` to Content-Type header without modification.
-# Rails.application.config.action_dispatch.return_only_media_type_on_content_type = false
-
-# Return false instead of self when enqueuing is aborted from a callback.
-Rails.application.config.active_job.return_false_on_aborted_enqueue = true
-
-# Send Active Storage analysis and purge jobs to dedicated queues.
-Rails.application.config.active_storage.queues.analysis = :active_storage_analysis
-Rails.application.config.active_storage.queues.purge    = :active_storage_purge
-
-# When assigning to a collection of attachments declared via `has_many_attached`, replace existing
-# attachments instead of appending. Use #attach to add new attachments without replacing existing ones.
-Rails.application.config.active_storage.replace_on_assign_to_many = true
-
-# Use ActionMailer::MailDeliveryJob for sending parameterized and normal mail.
-#
-# The default delivery jobs (ActionMailer::Parameterized::DeliveryJob, ActionMailer::DeliveryJob),
-# will be removed in Rails 6.1. This setting is not backwards compatible with earlier Rails versions.
-# If you send mail in the background, job workers need to have a copy of
-# MailDeliveryJob to ensure all delivery jobs are processed properly.
-# Make sure your entire app is migrated and stable on 6.0 before using this setting.
-Rails.application.config.action_mailer.delivery_job = "ActionMailer::MailDeliveryJob"
-
-# Enable the same cache key to be reused when the object being cached of type
-# `ActiveRecord::Relation` changes by moving the volatile information (max updated at and count)
-# of the relation's cache key into the cache version to support recycling cache key.
-Rails.application.config.active_record.collection_cache_versioning = true
-
-
-# The Rails 6 default autoloader is Zeitwerk. Zeitwerk has specific expectations on where certain
-# classes should be defined. It also requires that constants are not autoloaded in initializers.
-# Enabling Zeitwerk would be good, but it'll take some work. Using the :classic autoloader gives
-# us the same autoloading that Rails 5.2 had.
-# Rails.application.config.autoloader = :zeitwerk
-Rails.application.config.autoloader = :classic
diff --git a/config/initializers/sidekiq.rb b/config/initializers/sidekiq.rb
index 288453a0..1322c750 100644
--- a/config/initializers/sidekiq.rb
+++ b/config/initializers/sidekiq.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+require_relative '../../app/lib/sidekiq_error_handler'
+
 namespace    = ENV.fetch('REDIS_NAMESPACE') { nil }
 redis_params = { url: ENV['REDIS_URL'] }
 
diff --git a/config/initializers/suppress_csrf_warnings.rb b/config/initializers/suppress_csrf_warnings.rb
index 410ab585..41350c25 100644
--- a/config/initializers/suppress_csrf_warnings.rb
+++ b/config/initializers/suppress_csrf_warnings.rb
@@ -1,3 +1,3 @@
 # frozen_string_literal: true
 
-ActionController::Base.log_warning_on_csrf_failure = false
+Rails.application.config.action_controller.log_warning_on_csrf_failure = false
diff --git a/app/lib/exceptions.rb b/lib/exceptions.rb
similarity index 100%
rename from app/lib/exceptions.rb
rename to lib/exceptions.rb