Add explicit base class for ActiveJob jobs

* Jobs generated now inherent from ApplicationJob
* ApplicationJob inherents from ActiveJob::Base
* Added entry to changelog

Signed-off-by: Jeroen van Baarsen <jeroenvanbaarsen@gmail.com>

1 files changed, 15 insertions, 0 deletions

diff --git a/guides/source/upgrading_ruby_on_rails.md b/guides/source/upgrading_ruby_on_rails.md
index 05c46a9e76..5a6f267360 100644
--- a/guides/source/upgrading_ruby_on_rails.md
+++ b/guides/source/upgrading_ruby_on_rails.md
@@ -75,6 +75,21 @@ warning by adding the following configuration to your `config/application.rb`:
 
 See [#17227](https://github.com/rails/rails/pull/17227) for more details.
 
+### ActiveJob jobs now inherent from ApplicationJob by default
+
+In Rails 4.2 an ActiveJob inherents from `ActiveJob::Base`. In Rails 5.0 this
+behaviour has changed to now inherent from `ApplicationJob`.
+
+When upgrading from Rails 4.2 to Rails 5.0 you need to create a file
+`application_job.rb` in `app/jobs/` and add the following content:
+
+```
+class ApplicationJob < ActiveJob::Base
+end
+```
+
+See [#19034](https://github.com/rails/rails/pull/19034) for more details
+
 Upgrading from Rails 4.1 to Rails 4.2
 -------------------------------------