If you have Mount & Blade: Warband version 1.1 or above, you can upgrade your game to version 1.153 using this patch.
M&B Warband version 1.153
Troop AI for choosing weapon for different situations has been updated.
Ranged troop AI not being able to choose a target under certain circumstances bug has been fixed.
New operations for modders.
Some fixes and operation enhancements for modders.
Town economies are now more balanced.
Several other bug fixes.
Two new multiplayer maps have been added: Canyon and Desert Town.
HTTP communication has been rewritten due to connection issues reported by players.