PDOException: SQLSTATE[HY000]: General error: 2006 MySQL server has gone away

Stack trace:
at /srv/www/globalplaza.hu/gothic/db/pdo.php:44
0# /srv/www/globalplaza.hu/gothic/db/pdo.php:44:  PDOStatement->execute()
1# /srv/www/globalplaza.hu/gothic/db/pdo.php:55:  GtcPDO->smartQuery("SELECT c.id FROM gp3_content c WHERE c.url_mask = ? AND c.s_deleted = 0 AND c.mode = ? LIMIT 1", array(2))
2# /srv/www/globalplaza.hu/gothic/db/pdo.php:92:  GtcPDO->_query("SELECT c.id FROM gp3_content c WHERE c.url_mask = ? AND c.s_deleted = 0 AND c.mode = ? LIMIT 1", array(2))
3# /srv/www/globalplaza.hu/modules/content.php:135:  GtcPDO->getOne("SELECT c.id FROM gp3_content c WHERE c.url_mask = ? AND c.s_deleted = 0 AND c.mode = ? LIMIT 1", array(2))
4# /srv/www/globalplaza.hu/modules/content.php:251:  CachedAbstractContent->fixUpId()
5# /srv/www/globalplaza.hu/modules/content.php:718:  CachedAbstractContent->__construct("product", "product")
6# /srv/www/globalplaza.hu/product.php:90:  AbstractContent->__construct("product", "product")
7# /srv/www/globalplaza.hu/modules/frame.php:316:  Product->__construct()
8# /srv/www/globalplaza.hu/product.php:370:  SiteFrame("Product")