CTD - group reference not found

[Ekaton]

While playing before I've had a CTDs. Tried to undo the turn and do it again, still the same. Checked the game's log and it seems that it crashed because of this:

8:58:51 AM [Critical ] TRegion.DetachGroup Group reference not found in region (UID/Name) 1155 Salzburg Group (UID/Name) 1016518 Supply Depot 1805

Is there any way to fix that? I'm tired of this game running very poorly, and now it actually CTDs every time, rendering it entirely unplayable.