apache/pulsar · error · SchedulerManager.UnknownWorkerException

Worker ${workerId} is not among the current workers in the s

Error message

Worker ${workerId} is not among the current workers in the system

What it means

drainIfNotInProgress(workerId) checks the set of currently available workers; if the requested workerId is not among them it throws UnknownWorkerException ('Worker <id> is not among the current workers in the system'). You asked to drain a worker the cluster does not currently see as active.

Source

Thrown at pulsar-functions/worker/src/main/java/org/apache/pulsar/functions/worker/SchedulerManager.java:289

                }

                // A worker must be specified at this point. This would be set up by the caller.
                Objects.requireNonNull(workerId);

                // [We can get stricter, and require that every drain op be followed up with a cleanup of the
                // corresponding worker before any other drain op, so that the drainOpStatusMap should be empty
                // at the next drain operation.]
                if (drainOpStatusMap.containsKey(workerId)) {
                    String warnString = "Worker " + workerId
                            + " was not removed yet from SchedulerManager after previous drain op";
                    log.warn(warnString);
                    throw new WorkerNotRemovedAfterPriorDrainException();
                }

                if (!availableWorkers.contains(workerId)) {
                    log.info().attr("workerId", workerId)
                            .log("invokeDrain was called for a worker which is not currently active");
                    throw new UnknownWorkerException();
                }

                return drain(workerId);
            } finally {
                drainInProgressFlag.set(false);
            }
        } else {
            throw new DrainInProgressException();
        }
    }

    public LongRunningProcessStatus getDrainStatus(String workerId) {
        long startTime = System.nanoTime();
        LongRunningProcessStatus status = Optional.ofNullable(workerId).map(id ->
                Optional.ofNullable(drainOpStatusMap.get(id)).map(opStatus ->
                        switch (opStatus) {
                            case DrainCompleted ->
                                    LongRunningProcessStatus.forStatus(LongRunningProcessStatus.Status.SUCCESS);

View on GitHub (pinned to 820761864e)

Solutions

1. List current workers (worker stats / REST) and use an exact existing workerId.
2. Verify the worker's configured workerId matches the value you pass.
3. If the worker is gone, no drain is needed — just clean up its leftover assignment state if any.

Example fix

// before
worker.drainIfNotInProgress("worker-3"); // stale id
// after
if (!worker.getCurrentAvailableWorkers().contains("worker-3")) {
    log.warn("worker-3 is not active; nothing to drain");
    return;
}
worker.drainIfNotInProgress("worker-3");

// confirm the worker is currently active
if (!worker.getCurrentAvailableWorkers().contains(workerId)) {
    throw new IllegalArgumentException(workerId + " is not an active worker");
}

try {
    worker.drainIfNotInProgress(workerId);
} catch (UnknownWorkerException e) {
    log.warn("Worker {} not active; refresh worker list", workerId);
}

When it happens

Trigger: Draining a workerId that was already removed/never existed; typo in workerId; the target worker crashed or lost metadata-store registration before the drain call; calling drain after the worker already deregistered.

Common situations: Stale configuration or scripts referencing a decommissioned worker; retrying a drain after the worker already went away; hostname/worker-id mismatch (using hostname vs configured worker id).

Related errors

• Worker ${workerId} was not yet removed after a prior drain o
• Another drain is in progress
• You must specify either a Fully Qualified Function Name (FQF
• You must specify a name for the function or a Fully Qualifie
• Cannot specify both jar and function-type

AI-assisted analysis of apache/pulsar@820761864e (2026-09-06). Data as JSON: /api/errors/35caf95752e4a76b. Report an issue: GitHub.