Upgrade to a still supported version of oC? oC 6 is end-of-life since one year and even oC 7 reached end-of-life a few months ago:
https://central.owncloud.org/t/end-of-life-for-oc-7-please-upgrade-asap/848
There is really no point in trying to get this fixed. Either stay at PHP 5.4 or use PHP 5.6+ with a recent oC version.