Upon upgrade from previous versions, the first server startup produces errors in the log:
This is fine, since mysql_upgrade hasn't been run yet. However, after that mysql_upgrade also fails:
The second attempt to run mysql_upgrade, even right after the first failure, actually works:
and after that the server restarts without any errors.
Given that Debian packages run mysql_upgrade in the background (which means it doesn't make the server upgrade/startup fail), and RPM packages don't run mysql_upgrade at all, manual re-run of the failed mysql_upgrade is a viable workaround for the beta, but it should naturally be fixed.
Apparently upgrade from all versions is affected, I've seen it happen on upgrade from 10.0, 10.1, 10.2, 10.3.3, didn't try 5.5.