vitessio/vitess · error

vreplication engine is closed

Error message

vreplication engine is closed

What it means

Returned by the vreplication Engine when an operation (wrapped in the wg-tracked run function) is attempted after vre.Open() has not run or after Close() has been called. The engine holds mu and isOpen; any work requiring the engine (e.g. state transitions during shutdown) is rejected while it is closed.

Source

Thrown at go/vt/vttablet/tabletmanager/vreplication/engine.go:789

		}
		vre.controllers[id] = ct
	}
	log.Info(fmt.Sprintf("Completed transition for journal:workload %v", je))
}

// WaitForPos waits for the replication to reach the specified position.
func (vre *Engine) WaitForPos(ctx context.Context, id int32, pos string) error {
	start := time.Now()
	mPos, err := binlogplayer.DecodePosition(pos)
	if err != nil {
		return err
	}

	if err := func() error {
		vre.mu.Lock()
		defer vre.mu.Unlock()
		if !vre.isOpen {
			return errors.New("vreplication engine is closed")
		}

		// Ensure that the engine won't be closed while this is running.
		vre.wg.Add(1)
		return nil
	}(); err != nil {
		return err
	}
	defer vre.wg.Done()

	if vre.shortcircuit {
		return nil
	}

	dbClient := vre.dbClientFactoryFiltered()
	if err := dbClient.Connect(); err != nil {
		return err
	}

View on GitHub (pinned to 01a25a7d17)

Solutions

1. Retry after the tablet finishes its shutdown/restart cycle
2. Confirm the tablet started with vreplication enabled and check startup logs for engine-open failures
3. Serialize admin operations (vdiff, workflow state changes) with tablet restarts so they don't race Close()
4. Reopen the engine by restarting vttablet if it was never opened

Example fix

// before
// vdiff called while tablet is shutting down -> 'engine is closed'
// after
// wait for tablet readiness, then retry:
vtctldclient Workflow --keyspace ks vdiff sales start  // after tablet is up

if err := engineOp(); errors.Is(err, errClosed) || strings.Contains(err.Error(), "engine is closed") {
    // wait for tablet restart, then retry with backoff
    time.Sleep(2 * time.Second); retry()
}

When it happens

Trigger: Calling engine methods that use the protected run wrapper while the vreplication engine is closed — commonly during or after Close(), or on a tablet where the vreplication engine failed to open at startup.

Common situations: VDiff or vreplication state queries racing with tablet shutdown; engine never opened because startup initialization failed; calling VReplicationExec on a tablet with vreplication disabled.

Related errors

• work queue is not open
• VStreamer is not open
• VStreamer is not open
• BUG: thread with ID: %v must not access closed Throttler
• value out of range

AI-assisted analysis of vitessio/vitess@01a25a7d17 (2026-09-01). Data as JSON: /api/errors/be5d6cea202400d4. Report an issue: GitHub.