Related to bugs:
https://bugs.launchpad.net/ubuntu/+source/grub-installer/+bug/1258718
https://bugs.launchpad.net/ubuntu/+source/grub-installer/+bug/1254221
https://bugs.launchpad.net/ubuntu/+source/grub-installer/+bug/1252255
Related to bugs:
https:/ /bugs.launchpad .net/ubuntu/ +source/ grub-installer/ +bug/1258718
https:/ /bugs.launchpad .net/ubuntu/ +source/ grub-installer/ +bug/1254221
https:/ /bugs.launchpad .net/ubuntu/ +source/ grub-installer/ +bug/1252255