Hi Garry!
I would recomend to you, that you should test new Firmware in a Test Environment/Lab with your actual configs always before you roll it out to all your devices.
We had an issue with radius authentication from 15.x.x.x to 16.x.x.x. We couldnt log in from remote, the only way was the failsafe account.
So we had to do some reconfigurations on our Radius Servers cause we have a multivendor Network
GWG H