This is a new one for me and freaked me out until I was able to get to the boot menu. On the kernel 4.20.10-111 I get this error on boot.
EFI stub: ERROR: failed to read file. Trying to load files to higher address EFI stub: ERROR: failed to read file.
I am certain that I was able to boot on this kernel but was forced to use the other 4.18.5-90 which I am using as I write this.
The only thing that I did differently between last time my system was running and this start is the use of the Budgie Shutdown Applet set to a timer.