I had the error twice this evening, and have never seen it before. Annoyingly I am struggling to recreate it, however my first theory of it being a large update (i.e. lots of changes from the Editor) is not correct as I have just tried to recreate that unsuccessfully.
I don't know if this is related, but before the error appeared, my GT22 was acting very strangely. The Preset + and - IAs were taking me to Preset 129 when I was on a completely different preset. I did not change those buttons at all, and did not reboot the Axe-FX3, but after the Error 2 then that problem went away and the GT22 seems perfectly fine now (as it does most of the time). I've reported the same problem with slight differences in another thread, so I don't want to hijack this thread, however I thought I would mention it if it could be a clue/step closer to the Error 2 (or maybe they are completely different things).