In case anyone is following along (silent list!), I finally ran the debugger on JBRULES-2932 and found a suspicious bit of syntax that was accepted by Drools 5.1.1 but which causes Drools 5.2.0-SNAPSHOT to barf. https://issues.jboss.org/browse/JBRULES-2932?focusedCommentId=12591856#co... At issue is the following construction: answer.ID ( > 1 && < 4 ) || == 5 That parenthetical followed by an or-equals looks suspicious to me (dialect mvel). Although Drools 5.1.1 eats it just fine, should it? I want to tell my users to write the proper rule syntax; this doesn't look right to me. On the other hand, if it is proper syntax, I'd rather not change it, as there are hundreds of rules that use it. :-( Best, Laird -- View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/JBRULES-2932-suspicio... Sent from the Drools - Dev mailing list archive at Nabble.com.