13 files changed, 58 insertions, 76 deletions
diff --git a/guides/source/5_1_release_notes.md b/guides/source/5_1_release_notes.md
index fa92b9e5f8..80c9da6446 100644
--- a/guides/source/5_1_release_notes.md
+++ b/guides/source/5_1_release_notes.md
@@ -602,7 +602,7 @@ Please refer to the [Changelog][active-support] for detailed changes.
     ([Pull Request](https://github.com/rails/rails/pull/28157))
 
 *   Deprecated passing string to `:if` and `:unless` conditional options on `set_callback` and `skip_callback`.
-    ([Commit](https://github.com/rails/rails/commit/0952552)
+    ([Commit](https://github.com/rails/rails/commit/0952552))
 
 ### Notable changes
 
diff --git a/guides/source/action_controller_overview.md b/guides/source/action_controller_overview.md
index 2c3f74c3e1..5fb8e300de 100644
--- a/guides/source/action_controller_overview.md
+++ b/guides/source/action_controller_overview.md
@@ -400,9 +400,9 @@ Rails.application.config.session_store :cookie_store, key: '_your_app_session',
 Rails sets up (for the CookieStore) a secret key used for signing the session data in `config/credentials.yml.enc`. This can be changed with `bin/rails credentials:edit`.
 
 ```ruby
-# amazon:
-#  access_key_id: 123
-#  secret_access_key: 345
+# aws:
+#   access_key_id: 123
+#   secret_access_key: 345
 
 # Used as the base secret for all MessageVerifiers in Rails, including the one protecting cookies.
 secret_key_base: 492f...
diff --git a/guides/source/active_job_basics.md b/guides/source/active_job_basics.md
index 7a3ff12b63..914ef2c327 100644
--- a/guides/source/active_job_basics.md
+++ b/guides/source/active_job_basics.md
@@ -389,6 +389,25 @@ class GuestsCleanupJob < ApplicationJob
 end
 ```
 
+### Retrying or Discarding failed jobs
+
+It's also possible to retry or discard a job if an exception is raised during execution.
+For example:
+
+```ruby
+class RemoteServiceJob < ApplicationJob
+  retry_on CustomAppException # defaults to 3s wait, 5 attempts
+
+  discard_on ActiveJob::DeserializationError
+
+  def perform(*args)
+    # Might raise CustomAppException or ActiveJob::DeserializationError
+  end
+end
+```
+
+To get more details see the API Documentation for [ActiveJob::Exceptions](http://api.rubyonrails.org/classes/ActiveJob/Exceptions/ClassMethods.html).
+
 ### Deserialization
 
 GlobalID allows serializing full Active Record objects passed to `#perform`.
diff --git a/guides/source/active_support_core_extensions.md b/guides/source/active_support_core_extensions.md
index 1438245f9c..ae573cc77c 100644
--- a/guides/source/active_support_core_extensions.md
+++ b/guides/source/active_support_core_extensions.md
@@ -674,44 +674,6 @@ M.parents       # => [X::Y, X, Object]
 
 NOTE: Defined in `active_support/core_ext/module/introspection.rb`.
 
-### Reachable
-
-A named module is reachable if it is stored in its corresponding constant. It means you can reach the module object via the constant.
-
-That is what ordinarily happens, if a module is called "M", the `M` constant exists and holds it:
-
-```ruby
-module M
-end
-
-M.reachable? # => true
-```
-
-But since constants and modules are indeed kind of decoupled, module objects can become unreachable:
-
-```ruby
-module M
-end
-
-orphan = Object.send(:remove_const, :M)
-
-# The module object is orphan now but it still has a name.
-orphan.name # => "M"
-
-# You cannot reach it via the constant M because it does not even exist.
-orphan.reachable? # => false
-
-# Let's define a module called "M" again.
-module M
-end
-
-# The constant M exists now again, and it stores a module
-# object called "M", but it is a new instance.
-orphan.reachable? # => false
-```
-
-NOTE: Defined in `active_support/core_ext/module/reachable.rb`.
-
 ### Anonymous
 
 A module may or may not have a name:
@@ -745,7 +707,6 @@ end
 
 m = Object.send(:remove_const, :M)
 
-m.reachable? # => false
 m.anonymous? # => false
 ```
 
diff --git a/guides/source/association_basics.md b/guides/source/association_basics.md
index b5bd24d027..9616647f15 100644
--- a/guides/source/association_basics.md
+++ b/guides/source/association_basics.md
@@ -906,7 +906,7 @@ The `belongs_to` association supports these options:
 
 ##### `:autosave`
 
-If you set the `:autosave` option to `true`, Rails will save any loaded members and destroy members that are marked for destruction whenever you save the parent object.
+If you set the `:autosave` option to `true`, Rails will save any loaded association members and destroy members that are marked for destruction whenever you save the parent object. Setting `:autosave` to `false` is not the same as not setting the `:autosave` option. If the `:autosave` option is not present, then new associated objects will be saved, but updated associated objects will not be saved.
 
 ##### `:class_name`
 
@@ -1257,7 +1257,7 @@ Setting the `:as` option indicates that this is a polymorphic association. Polym
 
 ##### `:autosave`
 
-If you set the `:autosave` option to `true`, Rails will save any loaded members and destroy members that are marked for destruction whenever you save the parent object.
+If you set the `:autosave` option to `true`, Rails will save any loaded association members and destroy members that are marked for destruction whenever you save the parent object. Setting `:autosave` to `false` is not the same as not setting the `:autosave` option. If the `:autosave` option is not present, then new associated objects will be saved, but updated associated objects will not be saved.
 
 ##### `:class_name`
 
@@ -1653,7 +1653,7 @@ Setting the `:as` option indicates that this is a polymorphic association, as di
 
 ##### `:autosave`
 
-If you set the `:autosave` option to `true`, Rails will save any loaded members and destroy members that are marked for destruction whenever you save the parent object.
+If you set the `:autosave` option to `true`, Rails will save any loaded association members and destroy members that are marked for destruction whenever you save the parent object. Setting `:autosave` to `false` is not the same as not setting the `:autosave` option. If the `:autosave` option is not present, then new associated objects will be saved, but updated associated objects will not be saved.
 
 ##### `:class_name`
 
@@ -2176,7 +2176,7 @@ end
 
 ##### `:autosave`
 
-If you set the `:autosave` option to `true`, Rails will save any loaded members and destroy members that are marked for destruction whenever you save the parent object.
+If you set the `:autosave` option to `true`, Rails will save any loaded association members and destroy members that are marked for destruction whenever you save the parent object. Setting `:autosave` to `false` is not the same as not setting the `:autosave` option. If the `:autosave` option is not present, then new associated objects will be saved, but updated associated objects will not be saved.
 
 ##### `:class_name`
 
diff --git a/guides/source/autoloading_and_reloading_constants.md b/guides/source/autoloading_and_reloading_constants.md
index c62194faf4..ede0324a51 100644
--- a/guides/source/autoloading_and_reloading_constants.md
+++ b/guides/source/autoloading_and_reloading_constants.md
@@ -954,7 +954,7 @@ to work on some subclass, things get interesting.
 While working with `Polygon` you do not need to be aware of all its descendants,
 because anything in the table is by definition a polygon, but when working with
 subclasses Active Record needs to be able to enumerate the types it is looking
-for. Let’s see an example.
+for. Let's see an example.
 
 `Rectangle.all` only loads rectangles by adding a type constraint to the query:
 
@@ -963,7 +963,7 @@ SELECT "polygons".* FROM "polygons"
 WHERE "polygons"."type" IN ("Rectangle")
 ```
 
-Let’s introduce now a subclass of `Rectangle`:
+Let's introduce now a subclass of `Rectangle`:
 
 ```ruby
 # app/models/square.rb
@@ -978,7 +978,7 @@ SELECT "polygons".* FROM "polygons"
 WHERE "polygons"."type" IN ("Rectangle", "Square")
 ```
 
-But there’s a caveat here: How does Active Record know that the class `Square`
+But there's a caveat here: How does Active Record know that the class `Square`
 exists at all?
 
 Even if the file `app/models/square.rb` exists and defines the `Square` class,
@@ -1049,7 +1049,7 @@ end
 
 The purpose of this setup would be that the application uses the class that
 corresponds to the environment via `AUTH_SERVICE`. In development mode
-`MockedAuthService` gets autoloaded when the initializer runs. Let’s suppose
+`MockedAuthService` gets autoloaded when the initializer runs. Let's suppose
 we do some requests, change its implementation, and hit the application again.
 To our surprise the changes are not reflected. Why?
 
diff --git a/guides/source/caching_with_rails.md b/guides/source/caching_with_rails.md
index 910a531068..96650b5be9 100644
--- a/guides/source/caching_with_rails.md
+++ b/guides/source/caching_with_rails.md
@@ -181,7 +181,7 @@ cache.
 
 ### Shared Partial Caching
 
-It is possible to share partials and associated caching between files with different mime types. For example shared partial caching allows template writers to share a partial between HTML and Javascript files. When templates are collected in the template resolver file paths they only include the template language extension and not the mime type. Because of this templates can be used for multiple mime types. Both HTML and JavaScript requests will respond to the following code:
+It is possible to share partials and associated caching between files with different mime types. For example shared partial caching allows template writers to share a partial between HTML and JavaScript files. When templates are collected in the template resolver file paths they only include the template language extension and not the mime type. Because of this templates can be used for multiple mime types. Both HTML and JavaScript requests will respond to the following code:
 
 ```ruby
 render(partial: 'hotels/hotel', collection: @hotels, cached: true)
@@ -195,7 +195,7 @@ Another option is to include the full filename of the partial to render.
 render(partial: 'hotels/hotel.html.erb', collection: @hotels, cached: true)
 ```
 
-Will load a file named `hotels/hotel.html.erb` in any file mime type, for example you could include this partial in a Javascript file.
+Will load a file named `hotels/hotel.html.erb` in any file mime type, for example you could include this partial in a JavaScript file.
 
 ### Managing dependencies
 
diff --git a/guides/source/getting_started.md b/guides/source/getting_started.md
index 7c7b3a4c01..70a945ad9e 100644
--- a/guides/source/getting_started.md
+++ b/guides/source/getting_started.md
@@ -594,7 +594,7 @@ familiar error:
 You now need to create the `create` action within the `ArticlesController` for
 this to work.
 
-NOTE: by default `form_with` submits forms using Ajax thereby skipping full page
+NOTE: By default `form_with` submits forms using Ajax thereby skipping full page
 redirects. To make this guide easier to get into we've disabled that with
 `local: true` for now.
 
diff --git a/guides/source/i18n.md b/guides/source/i18n.md
index cb24822f86..0153f52249 100644
--- a/guides/source/i18n.md
+++ b/guides/source/i18n.md
@@ -1187,7 +1187,7 @@ If you find your own locale (language) missing from our [example translations da
 Resources
 ---------
 
-* [Google group: rails-i18n](https://groups.google.com/forum/#!forum/rails-i18n) - The project's mailing list.
+* [Google group: rails-i18n](https://groups.google.com/group/rails-i18n) - The project's mailing list.
 * [GitHub: rails-i18n](https://github.com/svenfuchs/rails-i18n) - Code repository and issue tracker for the rails-i18n project. Most importantly you can find lots of [example translations](https://github.com/svenfuchs/rails-i18n/tree/master/rails/locale) for Rails that should work for your application in most cases.
 * [GitHub: i18n](https://github.com/svenfuchs/i18n) - Code repository and issue tracker for the i18n gem.
 
diff --git a/guides/source/layouts_and_rendering.md b/guides/source/layouts_and_rendering.md
index 76b325d0bf..fe2477f2ae 100644
--- a/guides/source/layouts_and_rendering.md
+++ b/guides/source/layouts_and_rendering.md
@@ -71,23 +71,25 @@ If we want to display the properties of all the books in our view, we can do so
 <h1>Listing Books</h1>
 
 <table>
-  <tr>
-    <th>Title</th>
-    <th>Summary</th>
-    <th></th>
-    <th></th>
-    <th></th>
-  </tr>
-
-<% @books.each do |book| %>
-  <tr>
-    <td><%= book.title %></td>
-    <td><%= book.content %></td>
-    <td><%= link_to "Show", book %></td>
-    <td><%= link_to "Edit", edit_book_path(book) %></td>
-    <td><%= link_to "Remove", book, method: :delete, data: { confirm: "Are you sure?" } %></td>
-  </tr>
-<% end %>
+  <thead>
+    <tr>
+      <th>Title</th>
+      <th>Content</th>
+      <th colspan="3"></th>
+    </tr>
+  </thead>
+
+  <tbody>
+    <% @books.each do |book| %>
+      <tr>
+        <td><%= book.title %></td>
+        <td><%= book.content %></td>
+        <td><%= link_to "Show", book %></td>
+        <td><%= link_to "Edit", edit_book_path(book) %></td>
+        <td><%= link_to "Destroy", book, method: :delete, data: { confirm: "Are you sure?" } %></td>
+      </tr>
+    <% end %>
+  </tbody>
 </table>
 
 <br>
diff --git a/guides/source/plugins.md b/guides/source/plugins.md
index 0f0cde7634..b3a7f544f5 100644
--- a/guides/source/plugins.md
+++ b/guides/source/plugins.md
@@ -237,7 +237,7 @@ Finished in 0.004812s, 831.2949 runs/s, 415.6475 assertions/s.
 
 This tells us that we don't have the necessary models (Hickwall and Wickwall) that we are trying to test.
 We can easily generate these models in our "dummy" Rails application by running the following commands from the
-test/dummy directory:
+`test/dummy` directory:
 
 ```bash
 $ cd test/dummy
diff --git a/guides/source/security.md b/guides/source/security.md
index 2ac52155f8..0b2d8de0fb 100644
--- a/guides/source/security.md
+++ b/guides/source/security.md
@@ -1029,7 +1029,7 @@ Rails generates a `config/credentials.yml.enc` to store third-party credentials
 within the repo. This is only viable because Rails encrypts the file with a master
 key that's generated into a version control ignored `config/master.key` — Rails
 will also look for that key in `ENV["RAILS_MASTER_KEY"]`. Rails also requires the
-the key to boot in production, so the credentials can be read.
+key to boot in production, so the credentials can be read.
 
 To edit stored credentials use `bin/rails credentials:edit`.
 
@@ -1049,7 +1049,7 @@ If you want an exception to be raised when some key is blank, use the bang
 version:
 
 ```ruby
-Rails.application.credentials.some_api_key! # => raises KeyError: key not found: :some_api_key
+Rails.application.credentials.some_api_key! # => raises KeyError: :some_api_key is blank
 ```
 
 Additional Resources
diff --git a/guides/source/working_with_javascript_in_rails.md b/guides/source/working_with_javascript_in_rails.md
index 27cef2bd27..098366ec1b 100644
--- a/guides/source/working_with_javascript_in_rails.md
+++ b/guides/source/working_with_javascript_in_rails.md
@@ -382,7 +382,7 @@ Rails 5.1 introduced rails-ujs and dropped jQuery as a dependency.
 As a result the Unobtrusive JavaScript (UJS) driver has been rewritten to operate without jQuery.
 These introductions cause small changes to `custom events` fired during the request:
 
-NOTE: Signature of calls to UJS’s event handlers has changed.
+NOTE: Signature of calls to UJS's event handlers has changed.
 Unlike the version with jQuery, all custom events return only one parameter: `event`.
 In this parameter, there is an additional attribute `detail` which contains an array of extra parameters.