BPM Task API Approve action is throwing an error

Summary:

For one of the requirements, we need to call the bpm/api/4.0/tasks API to approve the resignation approval workflow.

As the first step, we are reassigning the workflow to the integration user and then attempting to approve the task using the same integration user. However, we are encountering the below error while trying to approve the task.

"detail": "Identity service cannot get users when identities size crosses limit   Fix: verify server log to find the problem cause",    "o:errorCode": "76012",    "o:errorPath": null,    "status": "400", "title": "Identity Service cannot get users

The API and request payload is mentioned below.

/bpm/api/4.0/tasks/{taskId}