I booted a Ubuntu LiveUSB on my Acer C720p and I got this error:
Missing parameter in configuration file. Keyword: path gfxboot.c32: not a COM32R image boot :
Pressing tab shows boot options: live live-install
But typing live and pressing Enter results in another error:
Not enough memory to load specified image boot:
The solution is to type live mem=1900m or whatever amount of memory you have.
Not enough memory to load specified image boot:live mem=1900m
Then Ubuntu LiveUSB will boot as normal.