Kernel panic - "not syncing: VFS: Unable to mount root fs on unknown block(0,0)"

[volcs0]

Tried upgrading to 6.0-beta12 from 5.0.5.

 

System posts fine, and I can choose Unraid from the boot menu.

 

Kernel panic is attached.

 

Going back to 5.0.5 (on the same stick) works fine.

 

Any help is appreciated.

 

Thanks.