Sudden error hoping to find the cause of it

Hi there

We recently got a serious error on the server and when I went through the logs the below error had pasted over 200 times in a short time period. I am wondering if anyone would know or recognise it so that I can narrow down where it came from or which plugin? A reboot did stop the error but I would love to know the cause if possible.

PLUGIN EXCEPTION ---->
java.lang.NullPointerException
at de.pbplugins.icListenerGuiInfo.lambda$onPlayerConnect$0(icListenerGuiInfo.java:110)
at pluginapi.PluginTimerManager.update(SourceFile:72)
at pluginapi.PluginManager.update(SourceFile:295)
at server.Main.update(SourceFile:286)
at commons.JIWApplication.update(SourceFile:324)
at com.jme3.system.NullContext.run(NullContext.java:133)
at java.lang.Thread.run(Thread.java:748)

##Exception: null
##Exception: java.lang.NullPointerException

Thanks for the replies. I have had other errors from iConomy plugin when combined with ActivSign so it would make sense then. I am glad it is just once off issues sporadically. Correct am using the latest version