After updating to owncloud 8.0.2 on Ubuntu 14.04, I was getting the following error in owncloud on the administration page “APCu below version 4.0.6 is installed, for stability and performance reasons we recommend to update to a newer APCu version.” I found this post on how to upgrade the php5-apcu package. Here is the link https://github.com/owncloud/core/issues/14386