How to print mensagens in the source code of the page using thymeleaf?

This is my code using jsp and jstl:

 <!-- 
        Failed to access a URL: ${url}
        Exception: ${exception}
     -->

How to do the same using Thymeleaf? This code below dont work:

  <--  <p>Failed to access a URL: <span  th:text="${ url}"></span></p> 
    <p>Exception: <span th:text="${exception}"></span></p> -->

When I do not comment it show the message on page:

Failed to access a URL: http://localhost:8080/blog-spring-thymeleaf/auth/login

Exception: org.springframework.web.servlet.NoHandlerFoundException: No handler found for GET /blog-spring-thymeleaf/auth/login