So I noticed a while ago some suggestion that this was a thing with some of the beta’s, but I figured that by this stage of development Apple would have resolved it for release. Nope... in fact make thy a hard nope. Upgrade resulted in black screen, power cycling did nothing, the fix for me was to do a Option+Shift+R and let it reinstall, at which point everything was as it should have been. Slightly disappointed that this was required, I know it’s old, but it’s my daily driver and it’s officially still supported.