Preparing to unpack .../grub-efi-amd64-signed_1.187.6~20.04.1+2.06-2ubuntu14.4_amd64.deb ... Unpacking grub-efi-amd64-signed (1.187.6~20.04.1+2.06-2ubuntu14.4) over (1.167+2.04-1ubuntu44) ... Preparing to unpack .../grub-efi-amd64-bin_2.06-2ubuntu14.4_amd64.deb ... Unpacking grub-efi-amd64-bin (2.06-2ubuntu14.4) over (2.04-1ubuntu44) ... Setting up grub-efi-amd64-bin (2.06-2ubuntu14.4) ... Setting up grub-efi-amd64-signed (1.187.6~20.04.1+2.06-2ubuntu14.4) ... The disk contains an unclean file system (0, 0). Metadata kept in Windows cache, refused to mount. Falling back to read-only mount because the NTFS partition is in an unsafe state. Please resume and shutdown Windows fully (no hibernation or fast restarting.) Could not mount read-write, trying read-only Installing grub to /var/lib/grub/esp. Installing for x86_64-efi platform. grub-install: error: /var/lib/grub/esp doesn't look like an EFI partition. Installing grub to /boot/efi. Installing for x86_64-efi platform. Installation finished. No error reported. dpkg: error processing package grub-efi-amd64-signed (--configure): installed grub-efi-amd64-signed package post-installation script subprocess returned error exit status 1