Without knowing the specifics of your existing system (use case, features utilised, custom features implemented, deployment model, build environment, user client, custom data model, intefaces used ... I could go on and on), it is impossible to answer that question without using a magic 8-ball. There can be any number of issues, it would take hours to list and then only a fraction might affect you (depending on circumstances and your skill).
So you need to be way more specific in your question(s) to potentially get a useful reply
