Hershey's implemented an enterprise-wide ERP system called Enterprise 21 to replace its legacy systems and prepare for Y2K. The $112 million project was rushed to meet an aggressive deadline, using a big bang approach. This led to major issues going live, including being unable to fulfill $100 million in orders for Halloween in 1999. Key mistakes included unrealistic timelines, a big bang implementation, integrating systems from multiple vendors, and a lack of oversight. Hershey's has since recovered through a slower, more thorough implementation of mySAP and investments to strengthen its logistics infrastructure.