I don't know the answer to your question, but those two MessageBox messages in a row are very funny!
Since you have the action "After state change has occured", I don't think so. However, and I am a complete newbie to Dispatch, if you set it to happen before the state change, then you should be able to abort the state change on error. I don't have dispatch in front of me right now, but I am failing state change on a dispatch filename check. I am doing production work, now, so I have not had much opportunity to work on it. If variable changes happen as part of the transition, you should be able to cheat those variables to the new variables in dispatch. There should be little risk of the state change happening if the dispatch command does run because EPDM wouldn't have allowed them to select change state if they didn't have access. I'm sorry I cannot be more help, but if you are a more advanced Dispatch user, maybe it will spark a thought.