Hi @ultimatemembersupport,
I chandge WordPress settings and now I can add cirilic user name, if I use WordPress registration form. I try delete
else if ( ! UM()->validation()->safe_username( $args[$key] ) ) {UM()->form()->add_error($key, __(‘Your username contains invalid characters’,’ultimate-member’) );
after that there was an opportunity to adding UserName with cirillic characters. But I think this is not correctly.