Why does my Spring Boot REST API return HTTP 415 Unsupported Media Type when sending JSON from Postman?

I am learning how REST APIs work in Spring Boot and found an issue when sending JSON data to a controller endpoint. My API returns: HTTP 415 Unsupported Media Type even though the JSON body itself seems valid. Controller example: @RestController @RequestMapping(“/users”) public class UserController { @PostMapping public String createUser(@RequestBody User user) { return “User created”; } } Model: public class User { private String name; private int age; public String getName() { return name; } public void setName(String name) { this.name = name; } public int getAge() { return age; } public voi