Kali linux 2.0 failed to connect to lvmetad.Falling back to device scanning
Solution 1:
(from: https://www.pckr.co.uk/arch-grub-mkconfig-lvmetad-failures-inside-chroot-install/ )
try first to disable lvmetad from /etc/lvm/lvm.conf and set use_lvmetad = 0
I had a similar problem on my Arch Linux VM, and following the commands in that blogpost I linked above helped me to get rid of that error.
I hope It helps, lemme know!