Форум

<?if (!empty($_SERVER['HTTP_REFERER'])):?>
    <a href="<?=$_SERVER['HTTP_REFERER']?>">Вернуться назад</a>
<?endif;?> 

<? if ($APPLICATION->GetCurPage(false) !== '/' && !defined("ERROR_404")) { ?>
                <main>
                    <div class="breadcrumbs-wr">
                        ...
                    </div>
                <? } ?>