diff --git a/Gemfile b/Gemfile
index 44388fc3..37f0440e 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,6 +1,6 @@
 source "https://rubygems.org"
 
-gem "rails", "~> 5.2.4.3"
+gem "rails", "~> 6.0.0"
 
 gem "mysql2"
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 6ff2c559..9c7dff21 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -2,56 +2,69 @@ GEM
   remote: https://rubygems.org/
   specs:
     Ascii85 (1.0.3)
-    actioncable (5.2.4.3)
-      actionpack (= 5.2.4.3)
+    actioncable (6.0.3.1)
+      actionpack (= 6.0.3.1)
       nio4r (~> 2.0)
       websocket-driver (>= 0.6.1)
-    actionmailer (5.2.4.3)
-      actionpack (= 5.2.4.3)
-      actionview (= 5.2.4.3)
-      activejob (= 5.2.4.3)
+    actionmailbox (6.0.3.1)
+      actionpack (= 6.0.3.1)
+      activejob (= 6.0.3.1)
+      activerecord (= 6.0.3.1)
+      activestorage (= 6.0.3.1)
+      activesupport (= 6.0.3.1)
+      mail (>= 2.7.1)
+    actionmailer (6.0.3.1)
+      actionpack (= 6.0.3.1)
+      actionview (= 6.0.3.1)
+      activejob (= 6.0.3.1)
       mail (~> 2.5, >= 2.5.4)
       rails-dom-testing (~> 2.0)
-    actionpack (5.2.4.3)
-      actionview (= 5.2.4.3)
-      activesupport (= 5.2.4.3)
+    actionpack (6.0.3.1)
+      actionview (= 6.0.3.1)
+      activesupport (= 6.0.3.1)
       rack (~> 2.0, >= 2.0.8)
       rack-test (>= 0.6.3)
       rails-dom-testing (~> 2.0)
-      rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    actionpack-page_caching (1.2.2)
+      rails-html-sanitizer (~> 1.0, >= 1.2.0)
+    actionpack-page_caching (1.2.3)
       actionpack (>= 5.0.0)
-    actionview (5.2.4.3)
-      activesupport (= 5.2.4.3)
+    actiontext (6.0.3.1)
+      actionpack (= 6.0.3.1)
+      activerecord (= 6.0.3.1)
+      activestorage (= 6.0.3.1)
+      activesupport (= 6.0.3.1)
+      nokogiri (>= 1.8.5)
+    actionview (6.0.3.1)
+      activesupport (= 6.0.3.1)
       builder (~> 3.1)
       erubi (~> 1.4)
       rails-dom-testing (~> 2.0)
-      rails-html-sanitizer (~> 1.0, >= 1.0.3)
-    activejob (5.2.4.3)
-      activesupport (= 5.2.4.3)
+      rails-html-sanitizer (~> 1.1, >= 1.2.0)
+    activejob (6.0.3.1)
+      activesupport (= 6.0.3.1)
       globalid (>= 0.3.6)
-    activemodel (5.2.4.3)
-      activesupport (= 5.2.4.3)
-    activerecord (5.2.4.3)
-      activemodel (= 5.2.4.3)
-      activesupport (= 5.2.4.3)
-      arel (>= 9.0)
+    activemodel (6.0.3.1)
+      activesupport (= 6.0.3.1)
+    activerecord (6.0.3.1)
+      activemodel (= 6.0.3.1)
+      activesupport (= 6.0.3.1)
     activerecord-typedstore (1.3.0)
       activerecord (>= 5.2)
-    activestorage (5.2.4.3)
-      actionpack (= 5.2.4.3)
-      activerecord (= 5.2.4.3)
+    activestorage (6.0.3.1)
+      actionpack (= 6.0.3.1)
+      activejob (= 6.0.3.1)
+      activerecord (= 6.0.3.1)
       marcel (~> 0.3.1)
-    activesupport (5.2.4.3)
+    activesupport (6.0.3.1)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 0.7, < 2)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
+      zeitwerk (~> 2.2, >= 2.2.2)
     addressable (2.7.0)
       public_suffix (>= 2.0.2, < 5.0)
     afm (0.2.2)
-    arel (9.0.0)
-    ast (2.4.0)
+    ast (2.4.1)
     bcrypt (3.1.13)
     builder (3.2.4)
     bullet (6.1.0)
@@ -86,9 +99,9 @@ GEM
     factory_bot_rails (5.2.0)
       factory_bot (~> 5.2.0)
       railties (>= 4.2.0)
-    faker (2.11.0)
+    faker (2.12.0)
       i18n (>= 1.6, < 2)
-    ffi (1.12.2)
+    ffi (1.13.1)
     globalid (0.4.2)
       activesupport (>= 4.2.0)
     good_migrations (0.0.2)
@@ -97,7 +110,7 @@ GEM
     hashdiff (1.0.1)
     hashery (2.1.2)
     htmlentities (4.3.4)
-    i18n (1.8.2)
+    i18n (1.8.3)
       concurrent-ruby (~> 1.0)
     jaro_winkler (1.5.4)
     jquery-rails (4.4.0)
@@ -126,7 +139,7 @@ GEM
       mini_portile2 (~> 2.4.0)
     oauth (0.5.4)
     parallel (1.19.1)
-    parser (2.7.1.2)
+    parser (2.7.1.3)
       ast (~> 2.4.0)
     pdf-reader (2.4.0)
       Ascii85 (~> 1.0.0)
@@ -140,37 +153,39 @@ GEM
     rack (2.2.3)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
-    rails (5.2.4.3)
-      actioncable (= 5.2.4.3)
-      actionmailer (= 5.2.4.3)
-      actionpack (= 5.2.4.3)
-      actionview (= 5.2.4.3)
-      activejob (= 5.2.4.3)
-      activemodel (= 5.2.4.3)
-      activerecord (= 5.2.4.3)
-      activestorage (= 5.2.4.3)
-      activesupport (= 5.2.4.3)
+    rails (6.0.3.1)
+      actioncable (= 6.0.3.1)
+      actionmailbox (= 6.0.3.1)
+      actionmailer (= 6.0.3.1)
+      actionpack (= 6.0.3.1)
+      actiontext (= 6.0.3.1)
+      actionview (= 6.0.3.1)
+      activejob (= 6.0.3.1)
+      activemodel (= 6.0.3.1)
+      activerecord (= 6.0.3.1)
+      activestorage (= 6.0.3.1)
+      activesupport (= 6.0.3.1)
       bundler (>= 1.3.0)
-      railties (= 5.2.4.3)
+      railties (= 6.0.3.1)
       sprockets-rails (>= 2.0.0)
     rails-dom-testing (2.0.3)
       activesupport (>= 4.2.0)
       nokogiri (>= 1.6)
     rails-html-sanitizer (1.3.0)
       loofah (~> 2.3)
-    railties (5.2.4.3)
-      actionpack (= 5.2.4.3)
-      activesupport (= 5.2.4.3)
+    railties (6.0.3.1)
+      actionpack (= 6.0.3.1)
+      activesupport (= 6.0.3.1)
       method_source
       rake (>= 0.8.7)
-      thor (>= 0.19.0, < 2.0)
+      thor (>= 0.20.3, < 2.0)
     rainbow (3.0.0)
     rake (13.0.1)
     rb-fsevent (0.10.4)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
     rb-readline (0.5.5)
-    regexp_parser (1.7.0)
+    regexp_parser (1.7.1)
     rexml (3.2.4)
     rotp (6.0.0)
       addressable (~> 2.7)
@@ -207,13 +222,13 @@ GEM
       activesupport
       rack (>= 1.1)
       rubocop (>= 0.72.0)
-    rubocop-rspec (1.39.0)
+    rubocop-rspec (1.40.0)
       rubocop (>= 0.68.1)
     ruby-enum (0.8.0)
       i18n
     ruby-progressbar (1.10.1)
     ruby-rc4 (0.1.5)
-    ruumba (0.1.14)
+    ruumba (0.1.16)
       rubocop
     safe_yaml (1.0.5)
     scenic (1.5.2)
@@ -222,7 +237,7 @@ GEM
     scenic-mysql_adapter (1.0.1)
       mysql2
       scenic (>= 1.4.0)
-    sitemap_generator (6.1.0)
+    sitemap_generator (6.1.2)
       builder (~> 3.0)
     sprockets (3.7.2)
       concurrent-ruby (~> 1.0)
@@ -251,11 +266,12 @@ GEM
       addressable (>= 2.3.6)
       crack (>= 0.3.2)
       hashdiff (>= 0.4.0, < 2.0.0)
-    websocket-driver (0.7.1)
+    websocket-driver (0.7.2)
       websocket-extensions (>= 0.1.0)
     websocket-extensions (0.1.5)
     xpath (3.2.0)
       nokogiri (~> 1.8)
+    zeitwerk (2.3.0)
 
 PLATFORMS
   ruby
@@ -284,7 +300,7 @@ DEPENDENCIES
   oauth
   pdf-reader
   puma
-  rails (~> 5.2.4.3)
+  rails (~> 6.0.0)
   rb-readline
   rotp
   rqrcode
diff --git a/app/models/tag.rb b/app/models/tag.rb
index b4057f03..f82e0db9 100644
--- a/app/models/tag.rb
+++ b/app/models/tag.rb
@@ -15,7 +15,7 @@ class Tag < ApplicationRecord
   attr_writer :filtered_count
 
   validates :tag, length: { maximum: 25 }, presence: true,
-                  uniqueness: true, format: { without: /,/ }
+                  uniqueness: { case_sensitive: true }, format: { without: /,/ }
   validates :description, length: { maximum: 100 }
   validates :hotness_mod, inclusion: { in: -10..10 }
   validates :permit_by_new_users, :privileged, inclusion: { in: [true, false] }
diff --git a/bin/setup b/bin/setup
index 94fd4d79..0e39e8cb 100755
--- a/bin/setup
+++ b/bin/setup
@@ -1,6 +1,5 @@
 #!/usr/bin/env ruby
 require 'fileutils'
-include FileUtils
 
 # path to your application root.
 APP_ROOT = File.expand_path('..', __dir__)
@@ -9,24 +8,22 @@ def system!(*args)
   system(*args) || abort("\n== Command #{args} failed ==")
 end
 
-chdir APP_ROOT do
-  # This script is a starting point to setup your application.
+FileUtils.chdir APP_ROOT do
+  # This script is a way to setup or update your development environment automatically.
+  # This script is idempotent, so that you can run it at anytime and get an expectable outcome.
   # Add necessary setup steps to this file.
 
   puts '== Installing dependencies =='
   system! 'gem install bundler --conservative'
   system('bundle check') || system!('bundle install')
 
-  # Install JavaScript dependencies if using Yarn
-  # system('bin/yarn')
-
   # puts "\n== Copying sample files =="
   # unless File.exist?('config/database.yml')
-  #   cp 'config/database.yml.sample', 'config/database.yml'
+  #   FileUtils.cp 'config/database.yml.sample', 'config/database.yml'
   # end
 
   puts "\n== Preparing database =="
-  system! 'bin/rails db:setup'
+  system! 'bin/rails db:prepare'
 
   puts "\n== Removing old logs and tempfiles =="
   system! 'bin/rails log:clear tmp:clear'
diff --git a/config/application.rb b/config/application.rb
index 9d846338..70042907 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -1,21 +1,19 @@
 require_relative 'boot'
 
-# included from https://github.com/rails/rails/blob/5-2-stable/railties/lib/rails/all.rb
-require 'rails'
-
-%w(
-  active_record/railtie
-  action_controller/railtie
-  action_view/railtie
-  action_mailer/railtie
-  rails/test_unit/railtie
-  sprockets/railtie
-).each do |railtie|
-  begin
-    require railtie
-  rescue LoadError
-  end
-end
+require "rails"
+# Pick the frameworks you want:
+require "active_model/railtie"
+# require "active_job/railtie"
+require "active_record/railtie"
+# require "active_storage/engine"
+require "action_controller/railtie"
+require "action_mailer/railtie"
+# require "action_mailbox/engine"
+# require "action_text/engine"
+require "action_view/railtie"
+# require "action_cable/engine"
+require "sprockets/railtie"
+require "rails/test_unit/railtie"
 
 # Require the gems listed in Gemfile, including any gems
 # you've limited to :test, :development, or :production.
diff --git a/config/environments/development.rb b/config/environments/development.rb
index e267083f..b8c063cd 100644
--- a/config/environments/development.rb
+++ b/config/environments/development.rb
@@ -16,9 +16,12 @@ Rails.application.configure do
   # Run rails dev:cache to toggle caching.
   if Rails.root.join('tmp', 'caching-dev.txt').exist?
     config.action_controller.perform_caching = true
+    config.action_controller.enable_fragment_cache_logging = true
 
     config.cache_store = :memory_store
-    config.public_file_server.headers = { 'Cache-Control' => "public, max-age=#{2.days.to_i}" }
+    config.public_file_server.headers = {
+      'Cache-Control' => "public, max-age=#{2.days.to_i}",
+    }
   else
     config.action_controller.perform_caching = false
 
@@ -47,7 +50,7 @@ Rails.application.configure do
   # Suppress logger output for asset requests.
   config.assets.quiet = true
 
-  # Raises error for missing translations
+  # Raises error for missing translations.
   # config.action_view.raise_on_missing_translations = true
 
   # Use an evented file watcher to asynchronously detect changes in source code,
diff --git a/config/environments/production.rb b/config/environments/production.rb
index cb88b1db..60a382fe 100644
--- a/config/environments/production.rb
+++ b/config/environments/production.rb
@@ -22,10 +22,12 @@ Rails.application.configure do
   # Apache or NGINX already handles this.
   config.public_file_server.enabled = ENV['RAILS_SERVE_STATIC_FILES'].present?
 
-  # Compress JavaScripts and CSS.
-  config.assets.js_compressor = :uglifier
+  # Compress CSS using a preprocessor.
   # config.assets.css_compressor = :sass
 
+  # Compress Javascript using a preprocessor.
+  config.assets.js_compressor = :uglifier
+
   # Do not fallback to assets pipeline if a precompiled asset is missed.
   config.assets.compile = false
 
@@ -52,9 +54,9 @@ Rails.application.configure do
   # Use a different cache store in production.
   # config.cache_store = :mem_cache_store
 
-  # Use a real queuing backend for Active Job (and separate queues per environment)
+  # Use a real queuing backend for Active Job (and separate queues per environment).
   # config.active_job.queue_adapter     = :resque
-  # config.active_job.queue_name_prefix = "lobsters_#{Rails.env}"
+  # config.active_job.queue_name_prefix = "lobsters_production"
 
   config.action_mailer.perform_caching = false
 
@@ -85,9 +87,33 @@ Rails.application.configure do
   # Do not dump schema after migrations.
   config.active_record.dump_schema_after_migration = false
 
+  # cache full pages for logged-out visitors without tag filters
   config.action_controller.page_cache_directory = "#{Rails.root}/public/cache"
+
+  # Inserts middleware to perform automatic connection switching.
+  # The `database_selector` hash is used to pass options to the DatabaseSelector
+  # middleware. The `delay` is used to determine how long to wait after a write
+  # to send a subsequent read to the primary.
+  #
+  # The `database_resolver` class is used by the middleware to determine which
+  # database is appropriate to use based on the time delay.
+  #
+  # The `database_resolver_context` class is used by the middleware to set
+  # timestamps for the last write to the primary. The resolver uses the context
+  # class timestamps to determine how long to wait before reading from the
+  # replica.
+  #
+  # By default Rails will store a last write timestamp in the session. The
+  # DatabaseSelector middleware is designed as such you can define your own
+  # strategy for connection switching and pass that into the middleware through
+  # these configuration options.
+  # config.active_record.database_selector = { delay: 2.seconds }
+  # config.active_record.database_resolver = ActiveRecord::Middleware::DatabaseSelector::Resolver
+  # config.active_record.database_resolver_context =
+  #   ActiveRecord::Middleware::DatabaseSelector::Resolver::Session
 end
 
+# disable some excessive logging in production
 %w{render_template render_partial render_collection}.each do |event|
   ActiveSupport::Notifications.unsubscribe "#{event}.action_view"
 end
diff --git a/config/environments/test.rb b/config/environments/test.rb
index e5ca07a5..369786f9 100644
--- a/config/environments/test.rb
+++ b/config/environments/test.rb
@@ -1,10 +1,11 @@
+# The test environment is used exclusively to run your application's
+# test suite. You never need to work with it otherwise. Remember that
+# your test database is "scratch space" for the test suite and is wiped
+# and recreated between test runs. Don't rely on the data there!
+
 Rails.application.configure do
   # Settings specified here will take precedence over those in config/application.rb.
 
-  # The test environment is used exclusively to run your application's
-  # test suite. You never need to work with it otherwise. Remember that
-  # your test database is "scratch space" for the test suite and is wiped
-  # and recreated between test runs. Don't rely on the data there!
   config.cache_classes = true
 
   # Disable caching when running tests
@@ -17,11 +18,14 @@ Rails.application.configure do
 
   # Configure public file server for tests with Cache-Control for performance.
   config.public_file_server.enabled = true
-  config.public_file_server.headers = { 'Cache-Control' => "public, max-age=#{1.hour.to_i}" }
+  config.public_file_server.headers = {
+    'Cache-Control' => "public, max-age=#{1.hour.to_i}",
+  }
 
   # Show full error reports and disable caching.
   config.consider_all_requests_local       = true
   config.action_controller.perform_caching = false
+  config.cache_store = :null_store
 
   # Raise exceptions instead of rendering exception templates.
   config.action_dispatch.show_exceptions = false
@@ -39,6 +43,6 @@ Rails.application.configure do
   # Print deprecation notices to the stderr.
   config.active_support.deprecation = :stderr
 
-  # Raises error for missing translations
+  # Raises error for missing translations.
   config.action_view.raise_on_missing_translations = true
 end
diff --git a/config/initializers/assets.rb b/config/initializers/assets.rb
index 8ebda7a5..8991cf49 100644
--- a/config/initializers/assets.rb
+++ b/config/initializers/assets.rb
@@ -5,8 +5,6 @@ Rails.application.config.assets.version = '2.0'
 
 # Add additional assets to the asset load path.
 # Rails.application.config.assets.paths << Emoji.images_path
-# Add Yarn node_modules folder to the asset load path.
-# Rails.application.config.assets.paths << Rails.root.join('node_modules')
 
 # Precompile additional assets.
 # application.js, application.css, and all non-JS/CSS in the app/assets
diff --git a/config/initializers/content_security_policy.rb b/config/initializers/content_security_policy.rb
index 109d2a48..8d612c74 100644
--- a/config/initializers/content_security_policy.rb
+++ b/config/initializers/content_security_policy.rb
@@ -23,6 +23,9 @@ end
 # Rails.application.config.content_security_policy_nonce_generator =
 #   -> request { SecureRandom.base64(16) }
 
+# Set the nonce only to specific directives
+# Rails.application.config.content_security_policy_nonce_directives = %w(script-src)
+
 # Report CSP violations to a specified URI
 # For further information see the following documentation:
 # https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy-Report-Only
diff --git a/config/initializers/new_framework_defaults_6_0.rb b/config/initializers/new_framework_defaults_6_0.rb
new file mode 100644
index 00000000..dd883802
--- /dev/null
+++ b/config/initializers/new_framework_defaults_6_0.rb
@@ -0,0 +1,52 @@
+# 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
+
+if Rails.application.config.respond_to?(:active_job)
+  # Return false instead of self when enqueuing is aborted from a callback.
+  Rails.application.config.active_job.return_false_on_aborted_enqueue = true
+end
+
+if Rails.application.config.respond_to?(:active_storage)
+  # 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
+end
+
+# 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
diff --git a/config/locales/en.yml b/config/locales/en.yml
index decc5a85..cf9b342d 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -27,7 +27,7 @@
 #   'true': 'foo'
 #
 # To learn more, please read the Rails Internationalization guide
-# available at http://guides.rubyonrails.org/i18n.html.
+# available at https://guides.rubyonrails.org/i18n.html.
 
 en:
   hello: "Hello world"