Error "The method withDefaultPasswordEncoder() is undefined for the type User" Spring Boot password

Remove your method userDetailsService. You need to override method from WebSecurityConfigurerAdapter:

protected void configure(AuthenticationManagerBuilder auth) throws Exception {..}

For example:

@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {

@Bean
public PasswordEncoder getPasswordEncoder() {
    return NoOpPasswordEncoder.getInstance();
}

@Override
protected void configure(AuthenticationManagerBuilder auth) throws Exception {

    auth.inMemoryAuthentication()
        .withUser("user1")
        .password("password1")
        .roles("ADMIN")
        .and()
        .withUser("user2")
        .password("password1")
        .roles("USER");
}

@Override
protected void configure(HttpSecurity http) throws Exception {

    http.authorizeRequests()
        .antMatchers("/user").hasAnyRole("ADMIN", "USER")
        .antMatchers("/admin").hasRole("ADMIN")
        .antMatchers("/").permitAll()
        .and()
        .formLogin();
}

}

You can check my repo: https://github.com/dmcheremisin/SpringBootSecurity/tree/master/basic.security

Additionally, good article(similar to my code): https://www.baeldung.com/java-config-spring-security