What causes "flow not found" in vxcontrol/pentagi?

Confirm the flow is active and the ID is correct.

flow not found

Error message

flow not found

What it means

GetFlowScreenshot returns the in-memory screenshot worker registered for a flow. If flowID is not present in the controller's map, it returns a plain "flow not found" error. Like the msg-log controller, this reflects runtime state only — workers exist only for currently loaded flows.

Source

Thrown at backend/pkg/controller/screenshots.go:64

func (sc *screenshotController) ListFlowsScreenshot(ctx context.Context) ([]FlowScreenshotWorker, error) {
	sc.mx.Lock()
	defer sc.mx.Unlock()

	flows := make([]FlowScreenshotWorker, 0, len(sc.flows))
	for _, flw := range sc.flows {
		flows = append(flows, flw)
	}

	return flows, nil
}

func (sc *screenshotController) GetFlowScreenshot(ctx context.Context, flowID int64) (FlowScreenshotWorker, error) {
	sc.mx.Lock()
	defer sc.mx.Unlock()

	flw, ok := sc.flows[flowID]
	if !ok {
		return nil, fmt.Errorf("flow not found")
	}

	return flw, nil
}

View on GitHub (pinned to ea665308ba)

Solutions

Confirm the flow is active and the ID is correct.
For finished flows, read screenshots from the database instead of the in-memory worker.
Handle this as a 404-class condition at the API boundary.
Refresh the flow list after backend restarts before issuing per-flow calls.

Example fix

null

Defensive patterns

Strategy: type-guard

Validate before calling

// confirm the flow is still active before requesting its screenshot worker
worker, err := flows.GetFlow(ctx, flowID)
if err != nil {
    return err // flow already gone
}

Type guard

func isFlowNotFoundError(err error) bool {
    return err != nil && strings.Contains(err.Error(), "flow not found")
}

Try / catch

flw, err := screenshots.GetFlowScreenshot(ctx, flowID)
if err != nil {
    if isFlowNotFoundError(err) {
        // fall back to DB-backed screenshot listing for finished flows
        return listScreenshotsFromDB(ctx, flowID)
    }
    return nil, err
}

Prevention

Avoid racing flow teardown: a flow removed by FinishFlow makes this lookup fail.
Keep a DB fallback for historical screenshots — the worker map is ephemeral.
Refresh flow state after backend restarts; workers are not rehydrated here.
Map this error to 404 at the API boundary.

When it happens

Trigger: Calling ScreenshotController.GetFlowScreenshot(ctx, flowID) for a flow that was never started, has finished (removed from the map on successful FinishFlow), or after a backend restart (in-memory workers are not restored here).

Common situations: Client fetching screenshots for a just-finished flow; stale flow ID cached in the frontend after restart; race between finishing a flow and a pending screenshot download; flow ID from a different environment.

Related errors

AI-assisted analysis of vxcontrol/pentagi@ea665308ba (2026-09-01). Data as JSON: /api/errors/4eb523179141260b. Report an issue: GitHub.