hashicorp/nomad · warning

error at index: %d, Err: %w

Error message

error at index: %d, Err: %w

What it means

While consuming the event channel, each received event carries its own Err field. When an individual streamed frame reports an error, captureEventStream counts it, logs it, and appends it to a multierror wrapped as 'error at index: N, Err: ...'. The capture loop keeps running; these errors surface at the end via mErrs.ErrorOrNil().

Source

Thrown at command/operator_debug.go:970

		}
		return fmt.Errorf("failed to stream events: %w", err)
	}

	eventCount := 0
	errCount := 0
	heartbeatCount := 0
	channelEventCount := 0

	var mErrs *multierror.Error

	for {
		select {
		case event := <-eventCh:
			channelEventCount++
			if event.Err != nil {
				errCount++
				c.verboseOutf("error from event stream: index; %d err: %v", event.Index, event.Err)
				mErrs = multierror.Append(mErrs, fmt.Errorf("error at index: %d, Err: %w", event.Index, event.Err))
				break
			}

			if event.IsHeartbeat() {
				heartbeatCount++
				continue
			}

			for _, e := range event.Events {
				eventCount++
				c.verboseOutf("Event: %4d, Index: %d, Topic: %-10s, Type: %s, FilterKeys: %s", eventCount, e.Index, e.Topic, e.Type, e.FilterKeys)

				bytes, err := json.Marshal(e)
				if err != nil {
					errCount++
					mErrs = multierror.Append(mErrs, fmt.Errorf("failed to marshal json from Topic: %s, Type: %s, Err: %w", e.Topic, e.Type, err))
				}

View on GitHub (pinned to 482b49bf1a)

Solutions

1. Inspect the wrapped Err for the specific index — it names the per-frame cause (timeout, EOF, 5xx)
2. Treat isolated occurrences as transient: rerun the capture to get a clean eventstream.json
3. If timeouts recur, keep the capture duration under the agent's blocking query limits or use an agent with higher query timeout settings
4. Verify agent health/stability (server/agent logs) if error frames appear repeatedly

func isEventError(ev events.Event) bool { return ev.Err != nil }

for event := range eventCh {
	if event.Err != nil {
		errs = multierror.Append(errs, fmt.Errorf("error at index: %d, Err: %w", event.Index, event.Err))
		continue // keep capturing later events
	}
}

When it happens

Trigger: The agent pushed an error frame onto the event channel — typically the blocking query timed out or was broken (agent restart, 5xx, RPC error) and the stream delivered an event whose Err is non-nil at a specific index.

Common situations: Long captures crossing the agent's blocking-query default timeout (10m) where the library re-blocks but surfaces an intermediate error; agent reload/restart during capture; transient network blips between client and agent.

Related errors

• failed to stream events: %w
• missing AllocID
• <remote node streaming RPC error relayed from ack.Error>
• subscription closed by server, client should resubscribe
• unexpected ExpirationLeeway type: %v

AI-assisted analysis of hashicorp/nomad@482b49bf1a (2026-09-04). Data as JSON: /api/errors/68d131a13731e0f4. Report an issue: GitHub.