Hi, I think I found a bug. When I use rule agent with directory scanner, and the rule that is being scanned contains a bug, then I receive a NPE instead of error message: java.lang.NullPointerException at org.drools.agent.FileScanner.readPackage(FileScanner.java:102) at org.drools.agent.FileScanner.getChangeSet(FileScanner.java:79) at org.drools.agent.FileScanner.loadPackageChanges(FileScanner.java:57) at org.drools.agent.DirectoryScanner.loadPackageChanges(DirectoryScanner.java:43) at org.drools.agent.RuleAgent.checkForChanges(RuleAgent.java:330) at org.drools.agent.RuleAgent.refreshRuleBase(RuleAgent.java:298) at org.drools.agent.RuleAgent.configure(RuleAgent.java:284) at org.drools.agent.RuleAgent.init(RuleAgent.java:208) at org.drools.agent.RuleAgent.newRuleAgent(RuleAgent.java:176) at org.drools.agent.RuleAgent.newRuleAgent(RuleAgent.java:164) ... (further entries of stack trace contains my application's lines) When I looked into code I found that DirectoryScanner object, used by the agent uses FileScanner object to scan each file in a directory. And the file scanner does not have a listener set. That's why the NPE is thrown. It's difficult to find a bug in the rule. I didn't find it in JIRA. If anyone knows, that it was reported, then I won't duplicate, otherwise, I think it is worth to create a report. Best regards, -- Przemysław Różycki AMG.net, A Bull Group Company ul. Łąkowa 29 90-554 Łódź www.amg.net.pl