Alan that's one risky way to do a transition from one sw release to another...
The more safe way is to set up a new server hardware (or back-up server hardware) with new SW version, after it is running with no errors in test mode, take "old" server offline and take "new" server online. Old server remains running as a fall back for some time. If it works with new SW on new server, the older server could be switched off after a couple of days and new SW can be installled on "old" server hardware. This server is then used as back-up server until next SW update.
That's the procedure that I am using for the measurment severs in my work life...
Ingo