UnionOfRAD/lithium — comment on commit 3d7bb6e9dce83a919805409ac379a3ac4609f266
File:  line 0
By jperras:

That probably means that the compatibility layer that Zend Server adds for simulating the APC API hasn't been updated to accomodate the newest APC versions (>=3.1.1), which includes a host of new functionality.

The real solution to this is to write a Zend Server cache adapter (here's the API: http://files.zend.com/help/Zend-Server-Community-Edition/zend_data_cache_-_php_api.htm), and disable the confusing APC API compatibility setting that is most likely enabled on your server.