Error trying import one category on page

As per the codex query_posts

Note: This function isn’t meant to be used by plugins or themes. As
explained later, there are better, more performant options to alter
the main query. Double Note: query_posts() is overly simplistic and
problematic way to modify main query of a page by replacing it with
new instance of the query. It is inefficient (re-runs SQL queries) and
will outright fail in some circumstances (especially often when
dealing with posts pagination). Any modern WP code should use more
reliable methods, like making use of pre_get_posts hook, for this
purpose. TL;DR don’t use query_posts() ever;

You should instead pass the category to wp_query

$args = array(
    'post_type' => 'post',
    'paged' => $paged,
    'tax_query' => array(
        array(
            'taxonomy' => 'category',
            'field' => 'slug',
            'terms' => 'fotos-fechadas'
    // Or with the ID
            'field' => 'id',
            'terms' => 19
        )
    )
);
$loop = new WP_Query( $args );