Unable to fullfill a coouple salesorder, script is throwing the erroor

"THE_KIT_DEFINITION_HAS_BEEN_CHANGED_PLEASE_USE_THE_UPDATE_ORDERS_KIT_MEMBERS_WITH_CURRENT_KIT_MEMBERS_MASS_UPDATE_IN_ORDER_TO_FULFILL_THIS_ORDER"

Have run Update Orders Kit Members with Current Kit Members for those orders, and issue still exist.

do you get the same error fulfilling via UI?

No, only in script.