nats-io/nats-server · error

UpdateConfig took %v

Error message

UpdateConfig took %v

What it means

A performance watchdog, not an error: fileStore.UpdateConfig took longer than 1 minute (logged via warn). Config updates lock the store and can trigger expensive limit enforcement/rebuilds, so this signals the operation is slow enough to matter for availability.

Source

Thrown at server/filestore.go:729

	// First enable sync after every write, so that any inflight
	// or subsequent write gets synced
	fs.updateDurabilitySettingsLocked(1)
	fs.mu.Unlock()

	// Sync all dirty blocks, so that we no longer have to rely
	// on the backing Raft WAL.
	fs.syncBlocks()

	fs.mu.RLock()
	defer fs.mu.RUnlock()
	return fs.werr
}

func (fs *fileStore) UpdateConfig(cfg *StreamConfig) error {
	start := time.Now()
	defer func() {
		if took := time.Since(start); took > time.Minute {
			fs.warn("UpdateConfig took %v", took.Round(time.Millisecond))
		}
	}()

	if fs.isClosed() {
		return ErrStoreClosed
	}
	if cfg.Name == _EMPTY_ {
		return fmt.Errorf("name required")
	}
	if cfg.Storage != FileStorage {
		return fmt.Errorf("fileStore requires file storage type in config")
	}
	if cfg.MaxMsgsPer < -1 {
		cfg.MaxMsgsPer = -1
	}

	fs.mu.Lock()
	new_cfg := FileStreamInfo{Created: fs.cfg.Created, StreamConfig: *cfg}

View on GitHub (pinned to 3a66a489d2)

Solutions

1. Reduce stream size or excessive limits (max msgs/bytes/subjects) that make enforcement slow
2. Schedule config changes off-peak on very large streams
3. Capture pprof profile during an update if the cause is unclear

When it happens

Trigger: Thrown at server/filestore.go:729 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of nats-io/nats-server@3a66a489d2 (2026-09-02). Data as JSON: /api/errors/d4e78c72dc1bd5da. Report an issue: GitHub.