Communication with system users has always been a key differentiator between successful and not-so-successful upgrades. Fully explaining the benefits for the company and changes in the end user experience (e.g., green screen to Web client, client to Web client, etc.) prior to the upgrade is critical in ensuring that the whole team supports the implementation.

End users don't like change because it causes them additional work. They would rather deal with the quirks and inefficiencies of an old system than test a new one. If the end user has a bad perception of the upgrade, it will hinder the overall effectiveness of the new system even if the software and hardware are fully functional. Communicate every way you can.

Most ERP systems come pre-set to handle a typical user load, but is your user load "typical"? If you assume that your user load is typical and find out you were wrong, you will cost your company much more time, effort and resources than if you correctly before going live. Comprehensive load-testing is best carried out by load-testing software with scripts and real users. Simply testing with just scripts will not provide you with the effects seen when a user makes a mistake. If you just test with people, you won't simulate the effect of batch jobs and electronic data interchange. Even if you test with one, rather than none, you will come out ahead.