QuantConnect/Lean · error · RegressionTestException

Expected stock assignment but got: {orderEvent}

Error message

Expected stock assignment but got: {orderEvent}

What it means

After the option assignment, the next expected Filled event is the stock (underlying) leg of the assignment: OrderType.OptionExercise, IsAssignment == false, Symbol == _stock. If the event is an assignment (duplicate), has the wrong symbol, or is a non-exercise fill, the regression fails.

Source

Thrown at Algorithm.CSharp/DuplicateOptionAssignmentRegressionAlgorithm.cs:96

                    LimitOrder(_option, 1, Securities[_option].Price * 0.1m);

                    _optionSold = true;
                }
                // This is the assignment
                else if (!_optionAssigned)
                {
                    if (orderEvent.Ticket.OrderType != OrderType.OptionExercise || !orderEvent.IsAssignment)
                    {
                        throw new RegressionTestException($"Expected option assignment but got: {orderEvent}");
                    }

                    _optionAssigned = true;
                }
                else if (!_stockAssigned)
                {
                    if (orderEvent.Ticket.OrderType != OrderType.OptionExercise || orderEvent.IsAssignment || orderEvent.Symbol != _stock)
                    {
                        throw new RegressionTestException($"Expected stock assignment but got: {orderEvent}");
                    }

                    _stockAssigned = true;
                }
                else
                {
                    throw new RegressionTestException($"Unexpected order fill event: {orderEvent}");
                }
            }
            else if (orderEvent.Status == OrderStatus.CancelPending)
            {
                // We receive the delisting warning before the order cancel is requested
                if (!_optionSold || !_optionAssigned || !_stockAssigned || !_optionDelistedWarningReceived)
                {
                    throw new RegressionTestException($"Unexpected cancel pending event: {orderEvent}");
                }
            }
            else if (orderEvent.Status == OrderStatus.Canceled)

View on GitHub (pinned to d2c3659f87)

Solutions

1. Verify _stock (AddEquity("GOOG").Symbol) matches the symbol on the exercise-delivery OrderEvent — account for mapped symbols.
2. Log orderEvent.Symbol, IsAssignment, and OrderType for the failing event.
3. Check for a Lean regression in option-exercise underlying-delivery event representation.
4. Compare the symbol using SID/canonical rather than raw Value if mapping is involved.

Example fix

// before
if (orderEvent.Ticket.OrderType != OrderType.OptionExercise || orderEvent.IsAssignment || orderEvent.Symbol != _stock)

// after — compare canonical symbol to handle mapping
if (orderEvent.Ticket.OrderType != OrderType.OptionExercise || orderEvent.IsAssignment || !orderEvent.Symbol.SID().Equals(_stock.SID()))

else if (!_stockAssigned)
{
    var isExerciseDelivery = orderEvent.Ticket.OrderType == OrderType.OptionExercise
        && !orderEvent.IsAssignment
        && orderEvent.Symbol == _stock;
    if (!isExerciseDelivery)
    {
        Debug($"Symbol mismatch? event={orderEvent.Symbol} stock={_stock}");
        throw new RegressionTestException($"Expected stock assignment but got: {orderEvent}");
    }
    _stockAssigned = true;
}

static bool IsStockDeliveryLeg(OrderEvent e, Symbol stock) =>
    e.Ticket.OrderType == OrderType.OptionExercise && !e.IsAssignment && e.Symbol == stock;

When it happens

Trigger: A second option-assignment event arrives instead of the underlying leg, the underlying delivery uses a different symbol than _stock (e.g., a mapped symbol), or an unexpected order fill interrupts the sequence.

Common situations: Symbol mapping (GOOG vs GOOCV) causing orderEvent.Symbol != _stock, a Lean change in how the underlying delivery event is represented, or a duplicate assignment event.

Related errors

• Expected option assignment but got: {orderEvent}
• Unexpected order fill event: {orderEvent}
• Option was not assigned
• Stock was not assigned
• Index is not tradable.

AI-assisted analysis of QuantConnect/Lean@d2c3659f87 (2026-08-13). Data as JSON: /api/errors/9dfa95a0a168c41c. Report an issue: GitHub.