grub-probe: warning: disk does not exist, so falling back to partition device /dev/sda1

I am attempting to get GRUB to boot Windows, but I ran into a problem. Whenever I try to run grub-probe --target=fs_uuid /mnt/bootmgr, I get this:

grub-probe: warning: disk does not exist, so falling back to partition device /dev/sda1.
grub-probe: warning: disk does not exist, so falling back to partition device /dev/sda1.
grub-probe: warning: disk does not exist, so falling back to partition device /dev/sda1.
grub-probe: error: disk `hostdisk//dev/sda1' not found.

/dev/sda1 absolutely exists. Why is this happening?

Solution 1:

The error messages are misleading. The disk exists, you just don't have access to them. Try running that command with sudo.