12 files changed, 31 insertions, 6 deletions
diff --git a/guides/bug_report_templates/action_controller_master.rb b/guides/bug_report_templates/action_controller_master.rb
index cf76de80d2..932d329943 100644
--- a/guides/bug_report_templates/action_controller_master.rb
+++ b/guides/bug_report_templates/action_controller_master.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+gem "bundler", "< 1.16"
+
 begin
   require "bundler/inline"
 rescue LoadError => e
diff --git a/guides/bug_report_templates/active_job_master.rb b/guides/bug_report_templates/active_job_master.rb
index ce480cbb52..36d9137b71 100644
--- a/guides/bug_report_templates/active_job_master.rb
+++ b/guides/bug_report_templates/active_job_master.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+gem "bundler", "< 1.16"
+
 begin
   require "bundler/inline"
 rescue LoadError => e
diff --git a/guides/bug_report_templates/active_record_master.rb b/guides/bug_report_templates/active_record_master.rb
index 78411e2d57..b66deb36f3 100644
--- a/guides/bug_report_templates/active_record_master.rb
+++ b/guides/bug_report_templates/active_record_master.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+gem "bundler", "< 1.16"
+
 begin
   require "bundler/inline"
 rescue LoadError => e
diff --git a/guides/bug_report_templates/active_record_migrations_master.rb b/guides/bug_report_templates/active_record_migrations_master.rb
index fce8d1d848..737ce66d7b 100644
--- a/guides/bug_report_templates/active_record_migrations_master.rb
+++ b/guides/bug_report_templates/active_record_migrations_master.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+gem "bundler", "< 1.16"
+
 begin
   require "bundler/inline"
 rescue LoadError => e
diff --git a/guides/bug_report_templates/benchmark.rb b/guides/bug_report_templates/benchmark.rb
index fb51273e3e..f5c88086a9 100644
--- a/guides/bug_report_templates/benchmark.rb
+++ b/guides/bug_report_templates/benchmark.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+gem "bundler", "< 1.16"
+
 begin
   require "bundler/inline"
 rescue LoadError => e
diff --git a/guides/bug_report_templates/generic_master.rb b/guides/bug_report_templates/generic_master.rb
index 384c8b1833..240571ba9a 100644
--- a/guides/bug_report_templates/generic_master.rb
+++ b/guides/bug_report_templates/generic_master.rb
@@ -1,5 +1,7 @@
 # frozen_string_literal: true
 
+gem "bundler", "< 1.16"
+
 begin
   require "bundler/inline"
 rescue LoadError => e
diff --git a/guides/rails_guides/levenshtein.rb b/guides/rails_guides/levenshtein.rb
index bafa6bfe9d..c48af797fa 100644
--- a/guides/rails_guides/levenshtein.rb
+++ b/guides/rails_guides/levenshtein.rb
@@ -38,7 +38,7 @@ module RailsGuides
         d[m] = x
       end
 
-      return x
+      x
     end
   end
 end
diff --git a/guides/source/5_1_release_notes.md b/guides/source/5_1_release_notes.md
index 80c9da6446..6b9a950a42 100644
--- a/guides/source/5_1_release_notes.md
+++ b/guides/source/5_1_release_notes.md
@@ -350,6 +350,10 @@ Please refer to the [Changelog][action-pack] for detailed changes.
 
 *   Removed deprecated methods related to controller filters.
     ([Commit](https://github.com/rails/rails/commit/d7be30e8babf5e37a891522869e7b0191b79b757))
+    
+*   Removed deprecated support to `:text` and `:nothing` in `render`.
+    ([Commit](https://github.com/rails/rails/commit/79a5ea9eadb4d43b62afacedc0706cbe88c54496), 
+    [Commit](https://github.com/rails/rails/commit/57e1c99a280bdc1b324936a690350320a1cd8111))
 
 ### Deprecations
 
diff --git a/guides/source/action_cable_overview.md b/guides/source/action_cable_overview.md
index 6ac6792e26..57403a4bf9 100644
--- a/guides/source/action_cable_overview.md
+++ b/guides/source/action_cable_overview.md
@@ -668,8 +668,8 @@ authentication. You can see one way of doing that with Devise in this [article](
 ## Dependencies
 
 Action Cable provides a subscription adapter interface to process its
-pubsub internals. By default, asynchronous, inline, PostgreSQL, evented
-Redis, and non-evented Redis adapters are included. The default adapter
+pubsub internals. By default, asynchronous, inline, PostgreSQL, and Redis
+adapters are included. The default adapter
 in new Rails applications is the asynchronous (`async`) adapter.
 
 The Ruby side of things is built on top of [websocket-driver](https://github.com/faye/websocket-driver-ruby),
diff --git a/guides/source/action_controller_overview.md b/guides/source/action_controller_overview.md
index d53c4dedf9..28f7246197 100644
--- a/guides/source/action_controller_overview.md
+++ b/guides/source/action_controller_overview.md
@@ -654,8 +654,8 @@ class UsersController < ApplicationController
     @users = User.all
     respond_to do |format|
       format.html # index.html.erb
-      format.xml  { render xml: @users}
-      format.json { render json: @users}
+      format.xml  { render xml: @users }
+      format.json { render json: @users }
     end
   end
 end
diff --git a/guides/source/autoloading_and_reloading_constants.md b/guides/source/autoloading_and_reloading_constants.md
index ede0324a51..dea87a18f8 100644
--- a/guides/source/autoloading_and_reloading_constants.md
+++ b/guides/source/autoloading_and_reloading_constants.md
@@ -330,11 +330,17 @@ its resolution next. Let's define *parent* to be that qualifying class or module
 object, that is, `Billing` in the example above. The algorithm for qualified
 constants goes like this:
 
-1. The constant is looked up in the parent and its ancestors.
+1. The constant is looked up in the parent and its ancestors. In Ruby >= 2.5,
+`Object` is skipped if present among the ancestors. `Kernel` and `BasicObject`
+are still checked though.
 
 2. If the lookup fails, `const_missing` is invoked in the parent. The default
 implementation of `const_missing` raises `NameError`, but it can be overridden.
 
+INFO. In Ruby < 2.5 `String::Hash` evaluates to `Hash` and the interpreter
+issues a warning: "toplevel constant Hash referenced by String::Hash". Starting
+with 2.5, `String::Hash` raises `NameError` because `Object` is skipped.
+
 As you see, this algorithm is simpler than the one for relative constants. In
 particular, the nesting plays no role here, and modules are not special-cased,
 if neither they nor their ancestors have the constants, `Object` is **not**
@@ -1178,6 +1184,8 @@ end
 
 #### Qualified References
 
+WARNING. This gotcha is only possible in Ruby < 2.5.
+
 Given
 
 ```ruby
diff --git a/guides/source/engines.md b/guides/source/engines.md
index a9b841e3bf..b226eac347 100644
--- a/guides/source/engines.md
+++ b/guides/source/engines.md
@@ -1501,6 +1501,7 @@ To hook into the initialization process of one of the following classes use the
 | `ActionController::Base`          | `action_controller`                  |
 | `ActionController::TestCase`      | `action_controller_test_case`        |
 | `ActionDispatch::IntegrationTest` | `action_dispatch_integration_test`   |
+| `ActionDispatch::SystemTestCase`  | `action_dispatch_system_test_case`   |
 | `ActionMailer::Base`              | `action_mailer`                      |
 | `ActionMailer::TestCase`          | `action_mailer_test_case`            |
 | `ActionView::Base`                | `action_view`                        |