I'm using Zend_Cache as Session Handler, which works fine. I'm not sure where this issue was introduced, but every time when the automatic_cleaning_factor will remove old keys, I'll see the following error:

Fatal error: Undefined class constant 'CLEANING_MODE_OLD' in library/Zend/Cache/Core.php on line 0 Call Stack: 1.0006 14868608 1. My_Session_SaveHandler_ZendCache->write() library/My/Session/SaveHandler/ZendCache.php:0 1.0006 14868920 2. Zend_Cache_Core->save() library/My/Session/SaveHandler/ZendCache.php:29

I'm calling Zend_Cache_core with liek the following:

   public function write($id, $sessionData) {
        $this->cache->save($sessionData, $id, array() , $this->maxLifetime);
        return true;
    }

Where $this->cache is a cache from cachemanager, in my exampel with Zend_Cache_Core as frontend and Zend_Cache_Backend_Memcache as backend.