I have this problem and i find (in internet, of course) way to fix it:
we need to edit file etc\grub.d\30_otheros
we can find string like this: search --no-floppy --fs-uuid --set 180c9d7e0c9d5798
and need change it like this: search --no-floppy --fs-uuid --set=root 180c9d7e0c9d5798
Then run command "sudo update-grub" and error is gone.
PS. I saw theme "dual boot Kali Linux" but i cant post to it somewhy.
