At present, the mission server can lag behind the BGS slightly, resulting in impossible missions. Most notably, delivery and data missions to factions that have retreated in the time between the cmdr taking the mission and their arrival at the destination, but also situations like wartime massacre missions when the war is over.
I suggest that upon arrival at the destination system, when the open missions are checked for updates such as time bonuses and so on, add a validity check to make sure the conditions that allowed the mission to be completed still exist - is the target faction still present in the system, if it's a massacre mission are the factions still at war, is the megaship still there in the case of a "disable the megaship turrets" mission, has a target facility changed hands so it's no longer owned by the target faction, and so on.
If the relevant conditions are not met, then the mission should be updated in a way that allows it to be completed, or else abandoned gracefully.
I suggest that upon arrival at the destination system, when the open missions are checked for updates such as time bonuses and so on, add a validity check to make sure the conditions that allowed the mission to be completed still exist - is the target faction still present in the system, if it's a massacre mission are the factions still at war, is the megaship still there in the case of a "disable the megaship turrets" mission, has a target facility changed hands so it's no longer owned by the target faction, and so on.
If the relevant conditions are not met, then the mission should be updated in a way that allows it to be completed, or else abandoned gracefully.
- Delivery missions, source/return, mining and passenger missions, if the mission target has retreated from the system, should be redirected to another station where the faction is present, your ship can land, and the station has the appropriate services (passenger lounge or mission board) to complete the mission. If no such station exists, the mission giver switches to the controlling faction of the original station and you continue as normal. ("Suchandsuch Corporation have ceased operations in this system, our representatives will handle any outstanding affairs")
- Completed massacre missions against no-longer-valid targets can be turned in for a reward as normal. Incomplete ones should be automatically abandoned with no penalty.
- If a settlement or installation changing hands matters, update the mission accordingly with a popup box - inform them of the new controlling faction and allow them to either call it off or continue at their discretion.
- If a megaship has moved, update the mission to tell them where it's moved to.