Error message providing no hint to the problem

I am receiving sometimes an error message which I do not understand.
Has anyone an idea where to look.

11:13:11.413 [ERROR] [org.quartz.core.JobRunShell         ] - Job DEFAULT.2017-04-08T11:13:11.412+02:00: Proxy for org.eclipse.xtext.xbase.lib.Procedures$Procedure0: [ | {
  sendCommand(<XFeatureCallImplCustom>,<XFeatureCallImplCustom>)
} ] threw an unhandled Exception: 
java.lang.RuntimeException: The name '<unkown>' cannot be resolved to an item or type.
	at org.eclipse.smarthome.model.script.interpreter.ScriptInterpreter.invokeFeature(ScriptInterpreter.java:112)[129:org.eclipse.smarthome.model.script:0.9.0.b4]
	at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter._doEvaluate(XbaseInterpreter.java:901)[145:org.eclipse.xtext.xbase:2.9.2.v20160428-1452]
	at org.eclipse.xtext.xbase.interpreter.impl.XbaseInterpreter._doEvaluate(XbaseInterpreter.java:864)[145:org.eclipse.xtext.xbase:2.9.2.v20160428-1452]
	at org.eclipse.xtext.xbase.interpreter.imp
....

Likely a “cron” based rule you have.

The ‘quartz’ bit is a clue that a timer is involved, though there is no way to guess that from that name. Could be a timer, could be a cron triggered rule.

Whatever it is, there is obviously a sendCommand involved, which may narrow the possibilities. It cannot find something that it expected to work with.

When exactly “sometimes” could be important.
Quite often, if you edit a rules file while timers are running, those running timers will fail later as the reloading of the edited rule file has destroyed their context.
That would be expected and nothing to worry about in normal use (when you are not editing rules)

If that is not the case, you might add logInfo to any suspected rules or timers, just before any sendCommand, to try and work which one(s) are to blame

Hi rossko57,
Thanks for your analysis. Pretty much what you have suggested i tried to do. But since the error message is not coming very often I failed to find the cause.

But maybe your theory that the time has lost its context could be the reason.

That should only happen if you have made changes; you might be able to work it out from how long after changes the problem pops up.