I am working on a simple servlet with thymeleaf that changes a text by pressing a button.
The problem is that when I run it as a Spring application in the Spring tool suite 4.4, it works, but when compiling it as a servlet and uploading it to a tomcat server, this error appears: 
Here the code:
MainController.java
package com.example.demo; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.GetMapping; @Controller public class MainController { @GetMapping("/saludo") public String saludo(Model model) { model.addAttribute("saludo", "bondia"); return "index"; } @GetMapping("/nosaludo") public String nosaludo(Model model) { model.addAttribute("saludo", "no te salud"); return "index"; } @GetMapping("/despido") public String despido(Model model) { model.addAttribute("saludo", "Adeu"); return "index"; } } ServletInicializer.java
package com.example.demo; import org.springframework.boot.builder.SpringApplicationBuilder; import org.springframework.boot.web.servlet.support.SpringBootServletInitializer; public class ServletInitializer extends SpringBootServletInitializer { @Override protected SpringApplicationBuilder configure(SpringApplicationBuilder application) { return application.sources(CreantServletApplication.class); } } index.html
<html xmlns:th="http://www.thymeleaf.org"> <head> </head> <body> <form action="./saludo"> <input type="submit" value="Saludar"> </form> <form action="./nosaludo"> <input type="submit" value="No saludar"> </form> <form action="./despido"> <input type="submit" value="Despedirse"> </form> <h1 th:text="${saludo}">Text que es modificara</h1> </body> </html> 