When I first encountered the problem, I first tried to let boot-repair (run from a live system) repair my Grub installation, since I'm not too familiar with the boot process on UEFI. It failed multiple times, even when I disabled Secure Boot and when I enabled the CSM and tried to install grub-pc.
In the end, the only solution that worked was to chroot into the installed system, purge all grub and shim packages and install the original versions. This is the current state of my installation: > apt-mark showhold grub-common grub-efi-amd64 grub-efi-amd64-bin grub-efi-amd64-signed grub2-common shim shim-signed > apt list --upgradable Listing... Done grub-common/artful-updates 2.02~beta3-4ubuntu7.1 amd64 [upgradable from: 2.02~beta3-4ubuntu7] grub-efi-amd64/artful-updates 2.02~beta3-4ubuntu7.1 amd64 [upgradable from: 2.02~beta3-4ubuntu7] grub-efi-amd64-bin/artful-updates 2.02~beta3-4ubuntu7.1 amd64 [upgradable from: 2.02~beta3-4ubuntu7] grub-efi-amd64-signed/artful-updates 1.85.1+2.02~beta3-4ubuntu7.1 amd64 [upgradable from: 1.85+2.02~beta3-4ubuntu7] grub2-common/artful-updates 2.02~beta3-4ubuntu7.1 amd64 [upgradable from: 2.02~beta3-4ubuntu7] shim/artful-updates 13-0ubuntu2 amd64 [upgradable from: 0.9+1474479173.6c180c6-1ubuntu1] shim-signed/artful-updates 1.33.1~17.10.1+13-0ubuntu2 amd64 [upgradable from: 1.32+0.9+1474479173.6c180c6-1ubuntu1] I'm sorry that I cannot provide more details here due to my lack of knowledge regarding the UEFI boot process. If you tell me what to look for, I can try to provide more information. And now that I know how to restore my system, I'd be happy to try and collect some information with the buggy versions installed. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1750351 Title: (Thinkpad T470) Boot loop after update To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/shim/+bug/1750351/+subscriptions -- ubuntu-bugs mailing list email@example.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs