NPE: Cannot invoke "String.getBytes()" because "key" is null

[remcowesterhoud]

Describe the bug

Evaluating a decision results in a NullPointerException. The NPE occurs during evaluation of a decision. It appears to be iterating over a map of variables and breaks when it encounters a variable with the key null.

To Reproduce

Not sure

Expected behavior

No NPE should occur. If any null values are possible we should be able to deal with them.

Log/Stacktrace

https://console.cloud.google.com/errors/detail/CP_pnKWJn4Ta9AE;service=zeebe;time=P7D?project=camunda-cloud-240911

Full Stacktrace

 java.lang.NullPointerException: Cannot invoke "String.getBytes()" because "key" is null
	at io.camunda.zeebe.feel.impl.FeelToMessagePackTransformer.$anonfun$writeValue$2(FeelToMessagePackTransformer.scala:50) ~[zeebe-feel-integration-8.0.0.jar:8.0.0]
	at scala.collection.immutable.Map$Map2.foreach(Map.scala:342) ~[scala-library-2.13.8.jar:?]
	at io.camunda.zeebe.feel.impl.FeelToMessagePackTransformer.writeValue(FeelToMessagePackTransformer.scala:49) ~[zeebe-feel-integration-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.feel.impl.FeelToMessagePackTransformer.$anonfun$writeValue$1(FeelToMessagePackTransformer.scala:42) ~[zeebe-feel-integration-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.feel.impl.FeelToMessagePackTransformer.$anonfun$writeValue$1$adapted(FeelToMessagePackTransformer.scala:42) ~[zeebe-feel-integration-8.0.0.jar:8.0.0]
	at scala.collection.immutable.List.foreach(List.scala:333) ~[scala-library-2.13.8.jar:?]
	at io.camunda.zeebe.feel.impl.FeelToMessagePackTransformer.writeValue(FeelToMessagePackTransformer.scala:42) ~[zeebe-feel-integration-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.feel.impl.FeelToMessagePackTransformer.toMessagePack(FeelToMessagePackTransformer.scala:27) ~[zeebe-feel-integration-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.dmn.impl.DmnScalaDecisionEngine.toMessagePack(DmnScalaDecisionEngine.java:170) ~[zeebe-dmn-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.dmn.impl.EvaluatedDmnScalaDecision.of(EvaluatedDmnScalaDecision.java:56) ~[zeebe-dmn-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.dmn.impl.DmnScalaDecisionEngine.lambda$getEvaluatedDecisions$1(DmnScalaDecisionEngine.java:162) ~[zeebe-dmn-8.0.0.jar:8.0.0]
	at scala.collection.immutable.List.foreach(List.scala:333) ~[scala-library-2.13.8.jar:?]
	at io.camunda.zeebe.dmn.impl.DmnScalaDecisionEngine.getEvaluatedDecisions(DmnScalaDecisionEngine.java:159) ~[zeebe-dmn-8.0.0.jar:8.0.0]
	at java.util.Optional.map(Unknown Source) ~[?:?]
	at io.camunda.zeebe.dmn.impl.DmnScalaDecisionEngine.evaluateDecisionById(DmnScalaDecisionEngine.java:105) ~[zeebe-dmn-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.bpmn.behavior.BpmnDecisionBehavior.evaluateDecisionInDrg(BpmnDecisionBehavior.java:182) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.bpmn.behavior.BpmnDecisionBehavior.lambda$evaluateDecision$3(BpmnDecisionBehavior.java:111) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.util.Either$Right.flatMap(Either.java:366) ~[zeebe-util-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.bpmn.behavior.BpmnDecisionBehavior.evaluateDecision(BpmnDecisionBehavior.java:109) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.bpmn.task.BusinessRuleTaskProcessor$CalledDecisionBehavior.lambda$onActivate$0(BusinessRuleTaskProcessor.java:89) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.util.Either$Right.flatMap(Either.java:366) ~[zeebe-util-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.bpmn.task.BusinessRuleTaskProcessor$CalledDecisionBehavior.onActivate(BusinessRuleTaskProcessor.java:89) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.bpmn.task.BusinessRuleTaskProcessor.onActivate(BusinessRuleTaskProcessor.java:40) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.bpmn.task.BusinessRuleTaskProcessor.onActivate(BusinessRuleTaskProcessor.java:21) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.bpmn.BpmnStreamProcessor.lambda$processEvent$2(BpmnStreamProcessor.java:128) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.util.Either$Right.ifRightOrLeft(Either.java:381) ~[zeebe-util-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.bpmn.BpmnStreamProcessor.processEvent(BpmnStreamProcessor.java:127) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.bpmn.BpmnStreamProcessor.lambda$processRecord$0(BpmnStreamProcessor.java:110) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.util.Either$Right.ifRightOrLeft(Either.java:381) ~[zeebe-util-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.bpmn.BpmnStreamProcessor.processRecord(BpmnStreamProcessor.java:107) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.streamprocessor.TypedRecordProcessor.processRecord(TypedRecordProcessor.java:54) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.streamprocessor.ProcessingStateMachine.lambda$processInTransaction$3(ProcessingStateMachine.java:300) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.db.impl.rocksdb.transaction.ZeebeTransaction.run(ZeebeTransaction.java:84) ~[zeebe-db-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.streamprocessor.ProcessingStateMachine.processInTransaction(ProcessingStateMachine.java:290) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.streamprocessor.ProcessingStateMachine.processCommand(ProcessingStateMachine.java:253) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.streamprocessor.ProcessingStateMachine.tryToReadNextRecord(ProcessingStateMachine.java:213) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.engine.processing.streamprocessor.ProcessingStateMachine.readNextRecord(ProcessingStateMachine.java:189) ~[zeebe-workflow-engine-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.util.sched.ActorJob.invoke(ActorJob.java:79) ~[zeebe-util-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.util.sched.ActorJob.execute(ActorJob.java:44) ~[zeebe-util-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.util.sched.ActorTask.execute(ActorTask.java:122) ~[zeebe-util-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.util.sched.ActorThread.executeCurrentTask(ActorThread.java:97) ~[zeebe-util-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.util.sched.ActorThread.doWork(ActorThread.java:80) ~[zeebe-util-8.0.0.jar:8.0.0]
	at io.camunda.zeebe.util.sched.ActorThread.run(ActorThread.java:189) ~[zeebe-util-8.0.0.jar:8.0.0] 

Environment:

• OS: Camunda Cloud
• Zeebe Version: Seen in 8.0.0 and 8.0.1

[remcowesterhoud]

@saig0 You might be interested in this one. I haven't been able to fully analyse where the problem was coming from.

[saig0]

@remcowesterhoud I'm also not sure how to reproduce it 😅 The issue seems to be in the DMN engine.

It would be good to see the DMN that was evaluated. Can we get the DMN from the cluster for root cause analysis?

[npepinpe]

@remcowesterhoud please try to get the the DMN to further analyze this.

The expected impact here is that the instance is blacklisted, so not visible to the user, but the cluster will keep "working". We also expect likelihood here to be low, as no one ran into this so far. I'll mark it as blocker/info and severity/mid for now, but tentatively, and once we have the DMN we should revise this.

[remcowesterhoud]

I have identified and reproduced the issue. See camunda/dmn-scala#142

[remcowesterhoud]

Will be fixed by #9361