How to fix error in spring page rendering?

Question

Java

Good day to all.

I am getting this error

Whitelabel Error Page

This application has no explicit mapping for /error, so you are seeing this as a fallback.
Tue Jul 13 11:50:39 GMT+04:00 2021
There was an unexpected error (type=Not Found, status=404).
No message available

controller

package org.purposetracking.controller;

import org.purposetracking.model.User;
import org.purposetracking.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.GetMapping;

@Controller
public class UserController {

@Autowired
private UserService userService;

@GetMapping("/users")
public String showUsers(Model model) {
Iterable users = userService.getAll();
model.addAttribute("users", users);
return "index";
}
}

application.properties

# ===============================
# = DATA SOURCE
# ===============================
# Set here configurations for the database connection
spring.datasource.url=jdbc:postgresql://localhost:5432/purposes-tracking
spring.datasource.username=postgres
spring.datasource.password=12332112
spring.datasource.driver-class-name=org.postgresql.Driver
# Keep the connection alive if idle for a long time (needed in production)
spring.datasource.testWhileIdle=true
spring.datasource.validationQuery=SELECT 1
# ===============================
# = JPA / HIBERNATE
# ===============================
# Show or not log for each sql query
spring.jpa.show-sql=true
# Hibernate ddl auto (create, create-drop, update): with "create-drop" the database
# schema will be automatically created afresh for every start of application
#spring.jpa.hibernate.ddl-auto=create-drop

# Naming strategy
spring.jpa.hibernate.naming.implicit-strategy=org.hibernate.boot.model.naming.ImplicitNamingStrategyLegacyHbmImpl
spring.jpa.hibernate.naming.physical-strategy=org.springframework.boot.orm.jpa.hibernate.SpringPhysicalNamingStrategy

# Allows Hibernate to generate SQL optimized for a particular DBMS
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.PostgreSQLDialect

Tell me, please, where to dig?

Answer 1

If the question is to see a clear error instead of Whitelabel, then dig towards the error handler. If the question is that the error does not occur at all, then dig logs to find its causes.