localhost 8050 page not found.Fix this. 
Spring Boot "application.properties":spring.datasource.url=jdbc:mysql://localhost:3306/springbootcrud
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
spring.datasource.username=root
spring.datasource.password=7788
server.port=8050
Interface "User Repository": 
import net.crud.springbootcrud.model.User;
import org.springframework.data.jpa.repository.JpaRepository;

public interface UserRepository extends JpaRepository<User, Long> {
}
Java file "UserController":
import net.crud.springbootcrud.model.User;
import net.crud.springbootcrud.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;
import org.springframework.web.bind.annotation.PostMapping;

import java.util.List;

@Controller
public class UserController {
    private final UserService userService;

    public UserController(UserService userService) {
        this.userService = userService;
    }

    @GetMapping("/users")
    public String findAll(Model model){
        List<User> users = userService.findAll();
        model.addAttribute("users",users);
        return "user-list";
    }
@GetMapping("/user-create")
    public String createUserForm(User user){
        return "user-create";
    }
    @PostMapping("/user-create")
    public String createUser(User user){
        userService.saveUser(user);
        return "redirect:/users";
    }
}   
Java file "User":
import jakarta.persistence.*;
import lombok.Data;

@Data
@Entity
@Table(name = "users")
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    @Column(name = "first name")
    private String firstName;
    @Column(name = "last name")
    private String lastName;
    @Column(name = "username")
    private String username;

    public String getUsername() {

        return username;
    }

}
Java file "UserService":
import net.crud.springbootcrud.model.User;
import net.crud.springbootcrud.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.Optional;

@Service
public class UserService {
    private final UserRepository userRepository;

    public UserService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    public User findById(Long id){
        Optional<User> userOptional = userRepository.findById(id);
        if(userOptional.isPresent()){
            return userOptional.get();
        }
        throw new IllegalArgumentException("User with id " + id + " doesn't exist");
    }
    public List<User> findAll(){
        return userRepository.findAll();
    }
    public User saveUser(User user){
        if(user.getUsername() == null || user.getUsername().isEmpty()){
            throw new IllegalArgumentException("Username can not be empty");
        }
        return userRepository.save(user);
    }
    public void deleteById(Long id){
        Optional<User> userOptional = userRepository.findById(id);
        if(userOptional.isPresent()){
            userRepository.deleteById(id);
        }
        else{
            throw new IllegalArgumentException("User with id " + id + " doesn't exist");
        }
    }
}
Java file "spirngbootcrudApplication":
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.error.ErrorController;
import org.springframework.web.bind.annotation.RequestMapping;

@SpringBootApplication
public class SpringbootcrudApplication implements ErrorController {

	private static final String PATH = "/error";

	@RequestMapping(value = PATH)
	public String error() {
		return "error"; // Return the path to your custom error page
	}


	public String getErrorPath() {
		return PATH;
	}

	@RequestMapping // Remove the value attribute to map to all paths
	public String handleError() {
// Handle the error and return the path to your custom error page
		return "error";
	}

	public static void main(String[] args) {
		SpringApplication.run(SpringbootcrudApplication.class, args);
	}
}
}