Perspective - Unexpected problem unregistering listener from session event bus

Hi all,

I’m getting the below error in my gateway logs referring to an expression binding on a Perspective label component. It seems to populate the error anytime I have the page active. Wondering if anyone has seen this before? The expression binding on props.text is:

{view.params.Label} + ": " + {view.params.Value} + " " + {view.params.Units}

I’m currently running 8.1 RC2 so it’s possible it is related to that.

Unexpected problem unregistering listener from session event bus

java.lang.IllegalArgumentException: missing event subscriber for an annotated method. Is com.inductiveautomation.perspective.gateway.binding.expression.ExpressionBindingTagListener$SessionEventListener@64bd4089 registered?
at com.google.common.eventbus.SubscriberRegistry.unregister(SubscriberRegistry.java:111)
at com.google.common.eventbus.EventBus.unregister(EventBus.java:201)
at com.inductiveautomation.perspective.gateway.binding.expression.ExpressionBindingTagListener.shutdown(ExpressionBindingTagListener.java:69)
at com.inductiveautomation.ignition.common.expressions.BoundTagExpression.shutdown(BoundTagExpression.java:102)
at com.inductiveautomation.ignition.common.expressions.AbstractExpression.shutdown(AbstractExpression.java:52)
at com.inductiveautomation.ignition.common.expressions.AbstractExpression.shutdown(AbstractExpression.java:52)
at com.inductiveautomation.ignition.common.expressions.FunctionExpression.shutdown(FunctionExpression.java:56)
at com.inductiveautomation.ignition.common.expressions.AbstractExpression.shutdown(AbstractExpression.java:52)
at com.inductiveautomation.ignition.common.expressions.FunctionExpression.shutdown(FunctionExpression.java:56)
at com.inductiveautomation.perspective.gateway.binding.PerspectiveExpression.shutdown(PerspectiveExpression.java:174)
at com.inductiveautomation.perspective.gateway.binding.expression.ExpressionBinding.shutdown(ExpressionBinding.java:61)
at com.inductiveautomation.perspective.gateway.model.AbstractBindingHarness.shutdown(AbstractBindingHarness.java:161)
at com.inductiveautomation.perspective.gateway.model.DesignerPageModel$BindingPreviewSupport.modify(DesignerPageModel.java:132)
at com.inductiveautomation.perspective.gateway.model.DesignerPageModel$DesignerHandlers.lambda$new$8(DesignerPageModel.java:310)
at com.inductiveautomation.ignition.common.util.ExecutionQueue$PollAndExecute.run(ExecutionQueue.java:210)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.base/java.lang.Thread.run(Unknown Source)

Same issue on my system for any screen object that has logic tied to it such as if this then “Running” else “Stopped” or tag + “:” +tag

It look like this error occurs if the same tag is used in a binding expression more then once such as Tag1/Tag1 or Tag1+Tag2/Tag1

I had this same issue, with a binding that had multiple references to the same tag.
Reorganizing the binding expression to only reference the tag once seemed to have made the problem go away.

We stumbled across the same problem in version 8.1.4 when having multiple references to the same tag on a Perspective component.
Is this the intended behavior or is this a bug? Why do expressions work differently here than they work somewhere else?

Yep, i’m running into the same issue.