I've got an mkusb live USB (Ubuntu 18.04 with persistence) that boots fine on some of my computers. On one laptop I get the following error:
error: disk `hd0,4' not found. error: you need to load the kernel first.
What do I need to do to, "load the kernel first"?
EDIT: An SD card occupying an SD slot was causing this issue. Removing the SD card allows mkusb to boot properly, and eliminates the error. Once booted I reinsert the SD card into the SD slot if I need to use it.