Kill It with Fire

Assuming you fully understand the requirements because an existing system is operational is a critical mistake. One of the advantages of building a new system is that the team is more aware of the unknowns. Existing systems can be a distraction. The software team treats the full-featured implementation of it as the MVP, no matter how large or how complex that existing system actually is. It’s simply too much information to manage. People become overwhelmed, and they get discouraged and demoralized. The project stalls and reinforces the notion that the modernization work is impossible.