This appears to have been caused by the publication of a grub2 security update on 12/15 without the corresponding grub2-signed package being published at the same time.
We have had similar issues in the past with publication of grub2 and grub2-signed to the -updates pockets; the proposed solution there won't help for the security pocket, however, since those publications don't go via -proposed. Subscribing the security team for comment. To fix your current problem, you should install the grub-efi- amd64-signed package. ** Changed in: linux (Ubuntu) Status: Triaged => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1528345 Title: grub or kernel update broke Secure Boot by putting grubx64.efi instead of shimx64.efi in EFI boot order To manage notifications about this bug go to: https://bugs.launchpad.net/hundredpapercuts/+bug/1528345/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs