Hello friends , the code :
$ultimatemember->classes[‘form’]->add_error( ‘user_login’, ‘Your username must not contain the word admin.’ )
it’s working fine! Thanks.
The problem is the WordPress version 4.7.4 and Ultimate member 1.3.84, when I try to insert either a radio button a dropdown controls . En WordPress version is 4.6.5 and Ultimate member 1.3.84, radio button or dropdown it WORKS PERFECTLY.