You tried to install grub to /dev/sda, which is partitioned using GPT, but your computer is booting in BIOS mode. You either need to create a 1 mb bios_grub partition on this disk, or install grub to a disk that is partitioned with MBR/DOS.
** Changed in: ubiquity (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1729366 Title: Win10 on existing hdd. Cannot install grub after installation of ubuntu on separate ssd To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1729366/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs