It appears as though there is some problems in your custom source instantiating the class. You can verify that the jar file is being loaded by running this: lsof -u flume |grep MyFlumeSource.jar If it is then you need to review your code to determine what is causing that exception, here are a few pointers: http://craftingjava.blogspot.com/2012/06/javalanginstantiationexception.html ... View more