Setting up grub-efi-amd64 (2.02~beta2-9ubuntu1.4) ...
Installing for x86_64-efi platform.
grub-install: error: cannot open `/boot/efi/EFI/ubuntu/System/Library/CoreServices/boot.efi': Read-only file system.
dpkg: error processing package grub-efi-amd64 (--configure):
 subprocess installed post-installation script returned error exit status 1
E: Sub-process /usr/bin/dpkg returned an error code (1)