Unable to Fetch Process Instances from External Task for Older Versions

Hello Camunda Community,

I am currently facing an issue with fetching process instances from an external task in older versions of my BPMN process. Despite successfully starting and reaching the process instances, I am unable to retrieve them when using the fetchAndLock API call for the external task. Here are the details of my setup and the steps I’ve taken:

Environment:
Camunda Version: 7.22
Database: MSSQL
Process Definition Key: Process_Juridico
External Task Topic: MinutaPrimeiraVersao

Process Definition:
I have deployed a BPMN process with an external task defined as follows:
<bpmn:serviceTask id="ST_GerarMinuta" name="Gerar 1ª versão minuta" camunda:asyncBefore="true" camunda:type="external" camunda:topic="MinutaPrimeiraVersao">

Issue Description:
Fetch Request: I am using the following JSON for my fetchAndLock request:

{
    "workerId": "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
    "maxTasks": 10,
    "usePriority": false,
    "topics": [
        {
            "topicName": "MinutaPrimeiraVersao",
            "lockDuration": 60000,
            "processDefinitionId": "Process_Juridico:16:070d6b48-9604-11ef-b409-96e23c5077e7",
            "variables": [
                "id_processo",
                "id_documento",
                "id_utilizador",
                "acesso_nome"
            ]
        }
    ]
}

Response: The response from the fetchAndLock call returns an empty array (), indicating that no tasks are being fetched.

Process Instance ID: I can confirm that there are active process instances with the following ID:
57ec99ef-43b4-11eb-8c2e-00505694760d

Status: The process instance is not ended and is actively waiting at the external task.

Questions:
What could be causing the fetchAndLock call to return an empty response, despite having an active process instance?

Is there any specific configuration I should check in the BPMN model for older versions?

Are there any known limitations or bugs related to fetching tasks from older process versions in Camunda?

I would appreciate any guidance or suggestions on how to troubleshoot this issue. Thank you for your help!

Best regards,
Pedro Ferreira

Hi @ferreiralmpedro

Did you check out the content of the ACT_RU_EXT_TASK table and whether the tasks you are looking for exist (same process definition ID and topic name)?

Hi @hassang

I checked the table you mentioned, and there are no records, but in the cockpit, the task exists. What could I be doing wrong?

The cockpit image…

The call

{
    "workerId": "XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX",
    "maxTasks": 10,
    "usePriority": false,
    "topics": [
        {
            "topicName": "MinutaPrimeiraVersao",
            "lockDuration": 60000,
            "processDefinitionId": "Process_Juridico:12:0c2ee32b-1d4d-11ed-acc0-00505694760d",
            "variables": [
                "id_processo",
                "id_documento",
                "id_utilizador",
                "acesso_nome"
            ]
        }
    ]
}