Add ActiveJob configuration / base class

app/jobs/application_job.rb

@@ -0,0 +1,7 @@
+class ApplicationJob < ActiveJob::Base
+  # Automatically retry jobs that encountered a deadlock
+  # retry_on ActiveRecord::Deadlocked
+
+  # Most jobs are safe to ignore if the underlying records are no longer available
+  # discard_on ActiveJob::DeserializationError
+end

config/application.rb

@@ -47,6 +47,8 @@ module Zammad
       'observer::_sla::_ticket_rebuild_escalation',
       'observer::_transaction'
 
+    config.active_job.queue_adapter = :delayed_job
+
     # REST api path
     config.api_path = '/api/v1'