ubuntu 20.04 grub symbol 'grub_calloc' not found (備忘録) - QiitaThe GRUB boot loader was previously installed to a disk that is no longer present, or whose unique identifier has changed for some reason. It is important to make sure that the installed GRUB core image stays in sync with GRUB modules and grub.cfg. Please check again to make sure that GRUB is written to the appropriate boot devices. If you're unsure which drive is designated as boot drive by your
