diff --git a/pkg/backtest/exchange.go b/pkg/backtest/exchange.go
index f5dfac234..e6708932d 100644
--- a/pkg/backtest/exchange.go
+++ b/pkg/backtest/exchange.go
@@ -151,6 +151,9 @@ func (e *Exchange) NewStream() types.Stream {
 }
 
 func (e *Exchange) SubmitOrders(ctx context.Context, orders ...types.SubmitOrder) (createdOrders types.OrderSlice, err error) {
+	if e.userDataStream == nil {
+		return createdOrders, fmt.Errorf("SubmitOrders should be called after userDataStream been initialized")
+	}
 	for _, order := range orders {
 		symbol := order.Symbol
 		matching, ok := e.matchingBook(symbol)
@@ -198,6 +201,9 @@ func (e *Exchange) QueryClosedOrders(ctx context.Context, symbol string, since,
 }
 
 func (e *Exchange) CancelOrders(ctx context.Context, orders ...types.Order) error {
+	if e.userDataStream == nil {
+		return fmt.Errorf("CancelOrders should be called after userDataStream been initialized")
+	}
 	for _, order := range orders {
 		matching, ok := e.matchingBook(order.Symbol)
 		if !ok {
diff --git a/pkg/strategy/flashcrash/strategy.go b/pkg/strategy/flashcrash/strategy.go
index bfc797ae9..dce180f84 100644
--- a/pkg/strategy/flashcrash/strategy.go
+++ b/pkg/strategy/flashcrash/strategy.go
@@ -129,11 +129,13 @@ func (s *Strategy) Run(ctx context.Context, orderExecutor bbgo.OrderExecutor, se
 		Window:   25,
 	})
 
+	session.UserDataStream.OnStart(func() {
+		s.updateOrders(orderExecutor, session)
+	})
+
 	session.MarketDataStream.OnKLineClosed(func(kline types.KLine) {
 		s.updateOrders(orderExecutor, session)
 	})
 
-	// TODO: move this to the stream onConnect handler
-	s.updateOrders(orderExecutor, session)
 	return nil
 }