Skip to main content
Kofax

Repeated instances of error: "Exception in thread 'KapowTechnologies.AbstractThreadPool.WorkerThread' java.lang.NullPointerException"

Summary

12426

If your RoboServer is being "pinged" by a Network Monitoring service to confirm that it is still on-line, you may notice repeated instances of the following stack trace appearing in your RoboServer output:

==========================================================

Exception in thread "KapowTechnologies.AbstractThreadPool.WorkerThread" java.lang.NullPointerException
at
com.kapowtech.robosuite.service.server.RoboServerBridgeSimpleRQLEngine.request(RoboServerBridgeSimpleRQLEngine.java:115)
at
com.kapowtech.robosuite.service.socket.server.SocketHandlerRunnable.run(SocketHandlerRunnable.java:91) 
at
kapow.util.AbstractThreadPool$WorkerThread.run(AbstractThreadPool.java:228)

Exception in thread "KapowTechnologies.AbstractThreadPool.WorkerThread" java.lang.NullPointerException
at
com.kapowtech.robosuite.service.server.RoboServerBridgeSimpleRQLEngine.request(RoboServerBridgeSimpleRQLEngine.java:115)
at
com.kapowtech.robosuite.service.socket.server.SocketHandlerRunnable.run(SocketHandlerRunnable.java:91)
at
kapow.util.AbstractThreadPool$WorkerThread.run(AbstractThreadPool.java:228)

==========================================================

In most cases, this is caused because the Network Monitoring utility is pinging the server on RoboServer's TCP Listening Port (50000 by default). When RoboServer encounters an incoming connection to it's TCP Listening Port, it expects to receive a Robot Query Language (RQL) request. Since the monitoring utility does not send an RQL request to the RoboServer, the Roboserver reports a NullPointerException as it was unable to locate an RQL request in the incoming request.

In most cases, the frequency of these messages appearing in the RoboServer log will match the frequency with which the third party utility sends its request to verify that the RoboServer process is still running.

Keywords: Kapow Web Data Server version 7.x, Kapow 8.0, 8.1, 8.2, NullPointerException, error, pinged

  • Was this article helpful?