Cannot find execution with id for external Task

Hi Camunda Team,

I am having a load of around 2000 process Instance with camunda version 11.
We have an external task implementation for the service task.
I am having 2 camunda nodes running with 5 external Task nodes.
maxTask = 1
lockDuration = 60000
After a certain time period I am facing this exception in my camunda engine
2019-08-13 13:53:40.065 WARN 1 — [nio-8080-exec-1] ExceptionHandler : org.camunda.bpm.engine.exception.NullValueException: Cannot find execution with id 9541e9d7-bdd1-11e9-bc26-7ea93146e9a9 for external task 9541e9d9-bdd1-11e9-bc26-7ea93146e9a9: execution is null
Please find attached file for complete logs for camunda engine and external Task client.
Timestamp = 2019-08-13 13:53:40.068
logs-from-camunda-in-camunda-deployment-58b4c968d-tlzk8.txt (48.6 KB)logs-from-create-task-plumbing-in-create-task-plumbing-deployment-86d886f97b-82wc8.txt (456.9 KB)

Don’t get any clue for this exception.
And in plumbing we get 500 response status because of this.
Is this issue occurring because we have more external task client comparing to camunda engine. So same time another worker get’s serverd for the same execution id?
How can we prevent this?
Any best practice or solution?

Thanks in Advance

Any suggestion ?

Hi @akkujain93,

I haven’t been able to find anything in the logs that you provided that would give me some idea of what might be the problem. Can you provide an example project where the issue is reproduced so that I can debug it on my side?

Best,
Nikola

BPMN has a single external task -
GetPriority.bpmn (2.3 KB)
Camunda configuration
application.txt (1.4 KB)

Just working with 20000 process instance in this plumbing with maxTask 1 or maxTask 50.

5 nodes of my external service and 2 nodes of camunda server.

Got this error in camunda server logs.
Let me know if you need more details.

Hi @akkujain93,

I just stumbled over this thread which may be related to your problem: Execution Id cannot be found

Hope this helps, Ingo

Hi Ingo,
Thanks for reply.
Yes, I started my issue with that thread only. But as Ivgi’s issue is resolved by that postgres solution. But not in my case. And the issue is still persisting.

Lock Duration value is more than required. Still, when we are testing it in bulk(Load Test), facing this issue.