Re: [rules-users] threw error java.lang.ClassCastException: org.drools.reteoo.FromNode$FromMemory cannot be cast to org.drools.reteoo.BetaMemory

Heh... this is definitely a workaround.. and not exactly an efficient one :) You are essentially recreating your runtime environment from scratch... a question now: after you "make new KB the default KB", what happens to your session(s)? Do you create a new one or do you keep using the previously instantiated one? The latter would be obviously wrong.. the former could be interesting. A bit of background: when you update a KB and there are "live" sessions with object inserted, all the facts are implicitly re-updated to see if they can match any new rule that has potentially been added. With your workaround, you lose all the state of the current session... IF this is something you can do, I would suggest to try this: do not use your workaround, but make sure you DISPOSE any existing session(s) before updating the KB (do not create a new one!) and only then create a new SESSION to process your next facts. If this never generates exceptions, it would possibly suggest that there is indeed a race/overlap between the KB update and the (ongoing) propagation of some fact. Thanks! Davide p.s. what about the possibility of deploying a customized drools version? On 05/15/2013 02:57 PM, mohdejaz74 wrote: