For all the common error scenarios there is a custom error page implemented at common/error.ftl, which is shown as follows:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1,
shrink-to-fit=no">
<meta name="description" content="">
<meta name="author" content="">
<title>Error : ${status}</title>
<link rel="stylesheet" type="text/css"
href="/webjars/bootstrap/4.0.0/css/bootstrap.min.css"/>
<!-- Custom styles for this template -->
<link href="/css/blog-post.css" rel="stylesheet">
</head>
<body>
<nav class="navbar navbar-expand-lg navbar-dark bg-dark fixed-top">
<div class="container">
<a class="navbar-brand" href="/">Blog Management System</a>
</div>
</nav>
<div class="container">
<div class="row">
<div class="col-lg-8">
<!-- Title -->
<h1 class="mt-4">${status}</h1>
<p>${exception.message}
</div>
</div>
</div>
</body>
</html>
The preceding page will show the HTTP status and exception.message in the page for easy troubleshooting regarding what went wrong.