"That's why they tell you to back up the settings before applying an upgrade."
I've just upgraded the firmware on a box that warned me if I had a stored setup file that was created with an earlier firmware version, it won't be accepted now, due to certain security change requirements.
So, you write things down, resulting in a long winded and painful restore - worse still if you didn't read the firmware revision notes beforehand. Ironicaly, that's what the stored setup file was supposed to cure.
A forehead slap moment if there ever was one.