I run a dual boot setup with Win8.1 and F20.
I today tried to upgrade my F20 system to F21 using FedUp on a up-to-date F20 system. When I rebooted after FedUp was done updating and chose the upgrade volume in my rEFInd, I get the the following error as also shown in the attached picture:
Kernel panic - Not syncing: VFC: Unable to mount root fs on unknown-block(0,0).
I'm able to load F20 just fine using the installed kernel 3.17.4.
Do anyone have an idea on what I can try to get on with the upgrade?