Upgraded a system to F42 beta which went just fine… AFTER a period of panic where the reboot to actually do the install led to a completely black screen, after a while my monitor started complaining there was no signal. In my case, the drive is luks-encrypted, and I need a prompt to unlock it. Eventually I ended up hitting the ESC key, so it went to the text-mode console, and there it was sitting, waiting for the passphrase. After entering that, the install started, completed, and everything is fine since.
Seems like something in this process changed, as I’ve never had this issue on any of my Fedora boxes when doing version upgrades - there’s always enough console graphics produced to be able to enter the passkey.