add_filter( 'the_password_form', 'wpse_71284_custom_post_password_msg' );

/**

• Add a message to the password form.

• @wp-hook the_password_form

• @param string $form

• @return string */ function wpse_71284_custom_post_password_msg( $form ) { // No cookie, the user has not sent anything until now. if ( ! isset ( $COOKIE[ 'wp-postpass' . COOKIEHASH ] ) ) return $form;

  // Translate and escape. $msg = esc_html__( 'La contraseña es incorrecta o ya ha sido utilizada.', 'your_text_domain' );

  // We have a cookie, but it doesn’t match the password. $msg = "$msg

  ";

  return $msg . $form; }

add_action('init', 'myStartSession', 1); add_action('wp_logout', 'myEndSession'); add_action('wp_login', 'myEndSession'); function myStartSession() { if(!session_id()) { session_start(); } } function myEndSession() { session_destroy (); }

if ( post_password_required() ) { $session_id = 'wp-postpass_' . get_the_ID(); //onload $current_cookie = wp_unslash($COOKIE[ 'wp-postpass' . COOKIEHASH ]); //get old cookie $old_cookie = isset( $_SESSION[ $session_id ] ) ? $_SESSION[ $session_id ] : ''; //set new session $_SESSION[ $session_id ] = $current_cookie; if ( $current_cookie != $old_cookie && !empty( $old_cookie ) ){ error_notification('Error! Authentication failed!'); } } ?>

add_filter( 'the_password_form', 'wpse_71284_custom_post_password_msg' );

/**
 * Add a message to the password form.
 *
 * @wp-hook the_password_form
 * @param   string $form
 * @return  string
 */
function wpse_71284_custom_post_password_msg( $form )
{
    // No cookie, the user has not sent anything until now.
    if ( ! isset ( $_COOKIE[ 'wp-postpass_' . COOKIEHASH ] ) )
        return $form;

    // Translate and escape.
    $msg = esc_html__( 'La contraseña es incorrecta o ya ha sido utilizada.', 'your_text_domain' );

    // We have a cookie, but it doesn’t match the password.
    $msg = "<p class='custom-password-message'>$msg</p>";

    return $msg . $form;
}

add_action('init', 'myStartSession', 1);
add_action('wp_logout', 'myEndSession');
add_action('wp_login', 'myEndSession');
function myStartSession() {
    if(!session_id()) {
        session_start();
    }
}
function myEndSession() {
    session_destroy ();
}


if ( post_password_required() ) {
       $session_id = 'wp-postpass_' . get_the_ID();
       //onload
       $current_cookie = wp_unslash($_COOKIE[ 'wp-postpass_' . COOKIEHASH ]);
       //get old cookie 
       $old_cookie = isset( $_SESSION[ $session_id ] ) ? $_SESSION[ $session_id ] : '';
       //set new session
       $_SESSION[ $session_id ] = $current_cookie;
       if ( $current_cookie != $old_cookie && !empty( $old_cookie ) ){
           error_notification('<b>Error!</b> Authentication failed!');
       }
   }
?>