I am using hibernate from 3.2.0 branch and jboss-cache-1.4.0.ga. I have discovered that the cache throws NPE when we are trying to remove unexciting data. The methods "destroy" and "writeLoad" do so. I just have analysed the existing code and found, that method "remove" do a check before calling "remove". In this method the key remove if "cache.get" returns not null. So I applied the same approach in methods "destroy" and "writeLoad". My test now works. But I do not sure. Are this versions of hibernate and jbossCache compatible? Can we use OptimisticeTreeCache or it is under construction?