A GRUB Loading Error always happens when you boot the computer. It can be caused by improper GRUB configuration, a wrong location of GRUS. Hi everybody, sometimes I got a "grub loadingread error", it's something random, after some reboots I can access normally to the kernel and. Grub is short for GNU GRand Unified Bootloader. To be simply put, it's a boot loader package from the GNU Linux project. It's the common and reference.