From 8884a74625abcd3b48bfe75f45541de69193f4bc Mon Sep 17 00:00:00 2001
From: n-kawahito <n-kawahito@iij.ad.jp>
Date: Fri, 18 Sep 2026 12:46:14 +0900
Subject: [PATCH 1/2] =?UTF-8?q?[ADD]=E3=82=A8=E3=83=A9=E3=83=BC=E7=94=BB?=
 =?UTF-8?q?=E9=9D=A2=E5=87=A6=E7=90=86=E3=82=92=E5=AE=9F=E8=A3=85=E3=81=97?=
 =?UTF-8?q?=E3=81=BE=E3=81=97=E3=81=9F?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../controller/ErrorController.java           | 12 +++++++
 src/main/resources/templates/error.html       | 32 +++++++++++++++++++
 2 files changed, 44 insertions(+)
 create mode 100644 src/main/java/com/example/demo/app/presentation/controller/ErrorController.java
 create mode 100644 src/main/resources/templates/error.html

diff --git a/src/main/java/com/example/demo/app/presentation/controller/ErrorController.java b/src/main/java/com/example/demo/app/presentation/controller/ErrorController.java
new file mode 100644
index 0000000..973d396
--- /dev/null
+++ b/src/main/java/com/example/demo/app/presentation/controller/ErrorController.java
@@ -0,0 +1,12 @@
+package com.example.demo.app.presentation.controller;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.GetMapping;
+
+@Controller
+public class ErrorController {
+	    @GetMapping("/error")
+	    public String showError() {
+	        return "error";
+	    }
+}
diff --git a/src/main/resources/templates/error.html b/src/main/resources/templates/error.html
new file mode 100644
index 0000000..2bf0229
--- /dev/null
+++ b/src/main/resources/templates/error.html
@@ -0,0 +1,32 @@
+<!DOCTYPE html>
+<html xmlns:th="http://www.thymeleaf.org">
+<head>
+<meta charset="UTF-8" name="viewport" content="width=device-width, initial-scale=1">
+<title>エラー</title>
+<link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.7/dist/css/bootstrap.min.css" rel="stylesheet">
+</head>
+<body>
+
+	</head>
+	<body>
+
+	    <div th:replace="~{header :: header}">
+	    </div>
+
+	    <div class="container text-center mt-5">
+
+	        <h2 class="text-danger">
+	            エラーが発生しました
+	        </h2>
+
+	        <p th:text="${errorMessage}"></p>
+
+	        <a class="btn btn-primary" th:href="@{/login}">
+	            ログイン画面へ
+	        </a>
+
+	    </div>
+	
+	<script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.7/dist/js/bootstrap.bundle.min.js"></script>
+</body>
+</html>
\ No newline at end of file

From 7719c002ff85a81761acb35f8a593f1a4003e193 Mon Sep 17 00:00:00 2001
From: n-kawahito <n-kawahito@iij.ad.jp>
Date: Fri, 18 Sep 2026 12:46:43 +0900
Subject: [PATCH 2/2] =?UTF-8?q?[ADD]=E5=85=B1=E9=80=9A=E4=BE=8B=E5=A4=96?=
 =?UTF-8?q?=E5=87=A6=E7=90=86=E3=82=92=E5=AE=9F=E8=A3=85=E3=81=97=E3=81=BE?=
 =?UTF-8?q?=E3=81=97=E3=81=9F?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../exception/GlobalExceptionHandler.java     | 22 +++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 src/main/java/com/example/demo/exception/GlobalExceptionHandler.java

diff --git a/src/main/java/com/example/demo/exception/GlobalExceptionHandler.java b/src/main/java/com/example/demo/exception/GlobalExceptionHandler.java
new file mode 100644
index 0000000..17c1c7f
--- /dev/null
+++ b/src/main/java/com/example/demo/exception/GlobalExceptionHandler.java
@@ -0,0 +1,22 @@
+package com.example.demo.exception;
+
+import org.springframework.ui.Model;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.bind.annotation.ExceptionHandler;
+
+@ControllerAdvice
+public class GlobalExceptionHandler {
+
+    @ExceptionHandler(Exception.class)
+    public String handleException(
+            Exception e,
+            Model model) {
+
+        model.addAttribute(
+                "errorMessage",
+                "システムエラーが発生しました。"
+                + "初めからやり直してください。");
+
+        return "error";
+    }
+}