This is a bug and easily reproducible:
1. Install Ubuntu 10.04 server
2. Upgrade to 12.04 server (reboot is okay)
3. Upgrade to 14.04 server (reboot fails with grub error)
We've had this issue for all systems which was upgraded from 10.04. Here is a work around which worked for us:
1. Install Ubuntu 10.04 server
2. Upgrade to 12.04 server (reboot is okay)
3. Upgrade to 14.04 server (do not reboot ! )
4. grub-install /dev/sda (reboot is okay)
This is a bug and easily reproducible:
1. Install Ubuntu 10.04 server
2. Upgrade to 12.04 server (reboot is okay)
3. Upgrade to 14.04 server (reboot fails with grub error)
We've had this issue for all systems which was upgraded from 10.04. Here is a work around which worked for us:
1. Install Ubuntu 10.04 server
2. Upgrade to 12.04 server (reboot is okay)
3. Upgrade to 14.04 server (do not reboot ! )
4. grub-install /dev/sda (reboot is okay)