Mensaje de error

• Warning: Cannot modify header information - headers already sent by (output started at /var/www/clients/client48/web737/web/includes/common.inc:2797) en drupal_send_headers() (línea 1499 de /var/www/clients/client48/web737/web/includes/bootstrap.inc).
• TypeError: Argument 1 passed to xmlsitemap_node_create_link() must be an instance of stdClass, boolean given, called in /var/www/clients/client48/web737/web/sites/all/modules/xmlsitemap/xmlsitemap_node/xmlsitemap_node.module on line 28 en xmlsitemap_node_create_link() (línea 194 de /var/www/clients/client48/web737/web/sites/all/modules/xmlsitemap/xmlsitemap_node/xmlsitemap_node.module).