Impossible Advancement
Level 47 player:
Level 9 barn, Food Capacity: 18300
Spring of Life build requirement: 18557 Food
Barn Upgrade Requirement: Keep Level 10
Keep Level 10 Requirement: Spring Of Life.
So this is either, impossible.
OR
As barn upgrade appears to go from 8800 to 10000, and food capacity is 18300. There is something else that contributes to total food capacity, besides the barn.
Any help? As I am now doing google research to try to figure out this game.