The dress rehearsal (or mock Go Live) should be performed under the "Exact" same conditions as the real Go Live (e.g., if Go Live is on a weekend, mock Go Live needs to be on a weekend). Small problems can be isolated and easily resolved in the most accurate mock Go Live. You don't want to get ready to Go Live and find out the office air conditioning isn't on during the weekends or a scheduled maintenance task runs every Saturday at 3 p.m. Eliminating as many variables as possible will keep the team cool under pressure and insure that the tens of thousands, or sometimes millions of dollars, spent on a system upgrade will not be delayed because of a preventable issue.

Today's ERP upgrades are electronically packaged to address systemwide issues with electronic software updates (ESU). These updates can touch thousands of objects within your system and are a large leap from yesteryear's "paper fixes" that would address a specific issue or "opportunity in the software." Even if a business process was working properly prior to the change, it must be tested because the large impact on your system that ESUs cause may have disrupted its previous functionality. Only painstakingly testing all business processes will mitigate any unwanted "opportunities" from entering your production environment.