Implementing an enterprise system in an organization is hard because

It requires that the organization make large changes to the way they operate without stopping all their business operations

It requires that the organization suspend all business operations while they implement and roll out the ERP system

It requires that the organization "stop" or "pause" different parts of the organization such as different departments or different divisions as they implement the ERP system

It requires an organization to seek help from other organizations who can cover their work while they implement the ERP system