Try restoring the example backup file from MDL-16513

Fatal error: require_once() [function.require]: Failed opening required '/fs1/www_root/tjh238/moodle_head/mod/workshop/form/accumulative/db/upgradelib.php' (include_path='/fs1/www_root/tjh238/moodle_head/lib/zend:/fs1/www_root/tjh238/moodle_head/lib/pear:.:/php/includes:/usr/share/pear:/var/www/html/includes') in /fs1/www_root/tjh238/moodle_head/mod/workshop/form/accumulative/backup/moodle1/lib.php on line 29