Bazaar developer reference

UnitOrdersCancelled

An announcement: the game cancelled a unit's orders. The values are the unit and one of these reasons. It runs before the game clears the unit's orders, so you can still read them inside it; give the unit new orders later rather than from inside it.

Reason Why
CIV_ORDERS_PROMOTION_READY the unit earned a promotion
CIV_ORDERS_CANNOT_LAND an air unit can no longer move to its target
CIV_ORDERS_NO_ROUTE_TO_BUILD no road can be built that way any more
CIV_ORDERS_ROUTE_BLOCKED the next tile on the road being built can no longer be entered
CIV_ORDERS_NO_PATH no path leads to the destination any more
CIV_ORDERS_PATH_LONGER the way there now takes more than two turns longer than when the move began
CIV_ORDERS_DESTINATION_BLOCKED the unit would end this turn on its destination, which it can no longer enter, on a move ordered before this turn

Where it fires