Answer to Question #98889 in Software Engineering for Aliasgar Ansari

Question

Why it is expensive and risky to replace legacy system with new system ?

Answer 1

Legacy system is typically working solution for one of the business problems, which have survived through different requirements changes and usually well adopted and optimized for. This is a huge job and experience, so the new system development from scratch is attempt to do all this job again. It takes much time and so it is expensive. And on the other hand development team will face with problems and tasks, that legacy system had solved. And solutions in legacy system are well tested. So it is some kind of risky, that team can fail to achieve the same success.