From 1519b49f8bea4f602eec0974df053d14af5a9064 Mon Sep 17 00:00:00 2001
From: kaiba <kaibadash@gmail.com>
Date: Mon, 6 Apr 2026 18:32:09 +0900
Subject: [PATCH 1/2] Show 404 errors if a task has been deleted.

---
 .../maintenance_tasks/application_controller.rb          | 4 ++++
 app/views/maintenance_tasks/not_found.html.erb           | 9 +++++++++
 lib/maintenance_tasks/engine.rb                          | 4 ----
 test/system/maintenance_tasks/tasks_test.rb              | 9 +++++++++
 4 files changed, 22 insertions(+), 4 deletions(-)
 create mode 100644 app/views/maintenance_tasks/not_found.html.erb

diff --git a/app/controllers/maintenance_tasks/application_controller.rb b/app/controllers/maintenance_tasks/application_controller.rb
index 0140cd49..0f672ad7 100644
--- a/app/controllers/maintenance_tasks/application_controller.rb
+++ b/app/controllers/maintenance_tasks/application_controller.rb
@@ -31,5 +31,9 @@ class ApplicationController < MaintenanceTasks.parent_controller.constantize
     end
 
     protect_from_forgery with: :exception
+
+    rescue_from Task::NotFoundError do |error|
+      render("maintenance_tasks/not_found", status: :not_found)
+    end
   end
 end
diff --git a/app/views/maintenance_tasks/not_found.html.erb b/app/views/maintenance_tasks/not_found.html.erb
new file mode 100644
index 00000000..2d8758b6
--- /dev/null
+++ b/app/views/maintenance_tasks/not_found.html.erb
@@ -0,0 +1,9 @@
+<% content_for :page_title, "Not Found" %>
+
+<div class="container has-text-centered">
+  <h1 class="title is-3 has-text-weight-bold">Task Not Found</h1>
+  <p class="subtitle is-5">The task you are looking for does not exist or has been deleted.</p>
+  <p>
+    <%= link_to "Back to Tasks", tasks_path, class: "button is-primary is-rounded" %>
+  </p>
+</div>
diff --git a/lib/maintenance_tasks/engine.rb b/lib/maintenance_tasks/engine.rb
index 185a22f3..847a86a4 100644
--- a/lib/maintenance_tasks/engine.rb
+++ b/lib/maintenance_tasks/engine.rb
@@ -32,9 +32,5 @@ class Engine < ::Rails::Engine
     config.after_initialize do
       JobIteration.max_job_runtime ||= 5.minutes
     end
-
-    config.action_dispatch.rescue_responses.merge!(
-      "MaintenanceTasks::Task::NotFoundError" => :not_found,
-    )
   end
 end
diff --git a/test/system/maintenance_tasks/tasks_test.rb b/test/system/maintenance_tasks/tasks_test.rb
index 5e973d87..584f90d0 100644
--- a/test/system/maintenance_tasks/tasks_test.rb
+++ b/test/system/maintenance_tasks/tasks_test.rb
@@ -259,6 +259,15 @@ class TasksTest < ApplicationSystemTestCase
       assert_button "Run", disabled: true
     end
 
+    test "show a not found Task" do
+      visit maintenance_tasks_path + "/tasks/Maintenance::DoesNotExist"
+
+      assert_title "Not Found"
+      assert_text "Task Not Found"
+      assert_text "The task you are looking for does not exist or has been deleted."
+      assert_link "Back to Tasks"
+    end
+
     test "visit main page through iframe" do
       visit root_path
 

From 4fac3f94c51f1c1a594c34bb6cd24ed7ae288d63 Mon Sep 17 00:00:00 2001
From: kaiba <kaibadash@gmail.com>
Date: Fri, 26 Jun 2026 18:32:21 +0900
Subject: [PATCH 2/2] Update test/system/maintenance_tasks/tasks_test.rb
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: Étienne Barrié <etienne.barrie@gmail.com>
---
 test/system/maintenance_tasks/tasks_test.rb | 1 +
 1 file changed, 1 insertion(+)

diff --git a/test/system/maintenance_tasks/tasks_test.rb b/test/system/maintenance_tasks/tasks_test.rb
index 584f90d0..f40094d5 100644
--- a/test/system/maintenance_tasks/tasks_test.rb
+++ b/test/system/maintenance_tasks/tasks_test.rb
@@ -263,6 +263,7 @@ class TasksTest < ApplicationSystemTestCase
       visit maintenance_tasks_path + "/tasks/Maintenance::DoesNotExist"
 
       assert_title "Not Found"
+      assert_includes page.driver.browser.logs.get(:browser).sole.message, "404"
       assert_text "Task Not Found"
       assert_text "The task you are looking for does not exist or has been deleted."
       assert_link "Back to Tasks"