Hello, I am trying to write a Flink application which receives data from Kafka, does processing on keyed windowed streams and sends results on a different topic. Shortly after the job is started it fails with a NullPointerException in StateTable.put(). I am really confused by this error, because I am not explicitly working with state and in the exception stack, I cannot find a reference to my own code. I'd really appreciate it if anyone would help me figure out what's going on. Here's the exception stack:
2021-08-16 16:28:54 2021-08-16 13:28:54,026 INFO org.apache.flink.runtime.executiongraph.ExecutionGraph [] - Window(TumblingEventTimeWindows(1800000), EventTimeTrigger, CredentialStuffingAlerter) -> Map -> Sink: xdr.azure.analytics.login.credential_stuffing (2/2) (4b3004e64d8e3202535dd5521bff3584) switched from RUNNING to FAILED on senso-api-lciople-credential-stuffing-taskmanager-1-2 @ ip-192-168-96-68.eu-central-1.compute.internal (dataPort=44941). 2021-08-16 16:28:54 java.lang.NullPointerException: null 2021-08-16 16:28:54 at org.apache.flink.runtime.state.heap.StateTable.put(StateTable.java:351) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at org.apache.flink.runtime.state.heap.StateTable.put(StateTable.java:159) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at org.apache.flink.runtime.state.heap.HeapListState.add(HeapListState.java:98) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at org.apache.flink.streaming.runtime.operators.windowing.WindowOperator.processElement(WindowOperator.java:422) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at org.apache.flink.streaming.runtime.tasks.OneInputStreamTask$StreamTaskNetworkOutput.emitRecord(OneInputStreamTask.java:191) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at org.apache.flink.streaming.runtime.io.StreamTaskNetworkInput.processElement(StreamTaskNetworkInput.java:204) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at org.apache.flink.streaming.runtime.io.StreamTaskNetworkInput.emitNext(StreamTaskNetworkInput.java:174) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at org.apache.flink.streaming.runtime.io.StreamOneInputProcessor.processInput(StreamOneInputProcessor.java:65) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at org.apache.flink.streaming.runtime.tasks.StreamTask.processInput(StreamTask.java:396) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at org.apache.flink.streaming.runtime.tasks.mailbox.MailboxProcessor.runMailboxLoop(MailboxProcessor.java:191) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at org.apache.flink.streaming.runtime.tasks.StreamTask.runMailboxLoop(StreamTask.java:617) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at org.apache.flink.streaming.runtime.tasks.StreamTask.invoke(StreamTask.java:581) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at org.apache.flink.runtime.taskmanager.Task.doRun(Task.java:755) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at org.apache.flink.runtime.taskmanager.Task.run(Task.java:570) ~[flink-dist_2.11-1.12.3.jar:1.12.3] 2021-08-16 16:28:54 at java.lang.Thread.run(Unknown Source) ~[?:?] 2021-08-16 16:28:54 2021-08-16 13:28:54,040 INFO org.apache.flink.runtime.executiongraph.ExecutionGraph [] - Job Flink Streaming Job (80895c82f109899577d166b4388c157d) switched from state RUNNING to RESTARTING.
