My problems apparently were caused by a defect filesystem on the EFI partition. I did dosfsck /dev/sda1. Afterwards, the installation did work without a glitch. This bug report can be closed.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1723508 Title: installation of GRUB on EFI system fails (manual partition) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1723508/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
