I just started using the JENNIFER. Among the instances located on the upper dashboard, a few of them became STOP. According to the error log, I noticed an error message of “java.lang.IllegalArgumentException: hostname can’t be null.” I did not apply anything other than the JVM arguments of instance. How will I be able to activate the monitoring of the instance? It will be much helpful if you could explain a way to reactivate the monitoring. Please refer to the attached image.