Can't get filling percentage

#0 /var/www/vhosts/workingperson.com/htdocs/lib/Zend/Cache/Backend/Memcached.php(403): Zend_Cache::throwException('Can't get filli...')
#1 /var/www/vhosts/workingperson.com/htdocs/lib/Zend/Cache/Backend/TwoLevels.php(493): Zend_Cache_Backend_Memcached->getFillingPercentage()
#2 /var/www/vhosts/workingperson.com/htdocs/lib/Zend/Cache/Backend/TwoLevels.php(173): Zend_Cache_Backend_TwoLevels->_getFastFillingPercentage('saving')
#3 /var/www/vhosts/workingperson.com/htdocs/lib/Zend/Cache/Core.php(381): Zend_Cache_Backend_TwoLevels->save('save('saveCache('