If you are planning to replace your old ERP System by a new ERP System including data migration by a hopefully qualified third party, and:
you do not validate the system including functions, records, and processes
you do not define a roll-back strategy / disaster recovery strategy
you do not verify all data migrated between data source and new system
you do not execute full and complete acceptance testing based on system requirements
you do not track issues and problems
you do not define system development procedures
you decide a system go-live or even final payment without final acceptance and approvals
it might go well, or maybe not – find an example here: Read More