this is a bug in code. I've created https://jira.jboss.org/jira/browse/JBCACHE-1408 for this. anonymous wrote : One other questions related to optimistic locking...is there anything I can do to switch an existing cache configured with pessimistic locking to optimistic locking? For existing caches, it appears that it can load the objects because they do not have the appropriate data versioning. Anything that can be done outside of reading the entire cache and writing it out again in optimistic mode? No way of updating the database directly, as the version is stored binary together with other data map. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4175396#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...