Make sure that the
current turn you are trying to run was
generated using patch 2. For example (I think Geo went into this somewhere on PBW, so someone correct me if I get this wrong), Game 1 has 5 players: A, B, C, D, and E. Players A and B upload their turn. Then the game owner requests that the game be upgraded to patch 2, and the PBW admins comply the same day (since they have nothing else to do with their time besides monitor the Admin Requests forum

). So now the Game Info page says that the game is running patch 2.
However, players C, D, and E must submit their turns using
patch 1, since the turn they have was generated using patch 1. Not until after C, D, and E submit their turn and the PBW server generates the next turn
using patch 2 should the players switch over to patch 2.
I hope that wasn't too confusing...
EDIT: P.S. I got the same error when I updated too soon. See the patch 1.78 thread in the General discussions forum on PBW for my experiences (among those of others...)
[ August 18, 2002, 08:05: Message edited by: dumbluck ]