Ok, I am able to re-produce the problem now by deploying the kitchensink-ear. Just create a new member registration and then showdown the server (CTRL-C will work). The issue is really unrelated to where and how you start/stop the server. The reason it appears now is that only since CR1 the ValidatorFactory#close method is called (see WFLY-2602). Not sure yet why this NullPointerException occurs in the first place though.