Error message

• Warning: Cannot modify header information - headers already sent by (output started at /var/www/html/includes/common.inc:2861) in drupal_send_headers() (line 1554 of /var/www/html/includes/bootstrap.inc).
• TypeError: xml_set_element_handler(): Argument #1 ($parser) must be of type XMLParser, bool given in xml_set_element_handler() (line 78 of /var/www/html/modules/aggregator/aggregator.parser.inc).