Public bug reported: Almost identical to bug #1925010, but the T420 is an UEFI v2.00 machine, so I'm filing this separate bug.
This is a T420 in uefi mode, but not secure boot. I was running groovy, and just upgraded to hirsute with do-release-upgrade -d. It just wouldn't boot from the disk anymore after that. Black screen, no disk activity, no ctrl-alt-del response. I always had to power cycle it. I then performed the steps from comment 2 of that bug, and the machine booted normally after that: """ Can you please check that the machine boots with just grub without shim. Aka, replace /EFI/Boot/BOOTX64.efi & /ef/ubuntu/shimx64.efi files wtih /efi/ubuntu/grubx64.efi => this could possibly be a workaround, given that secureboot is not possible on Mac platforms. """ My BIOS version is 1.49 (83ET79WW), model is 4177CTO. I can attach more info if needed, and it's also simple to restore the buggy behavior. dmesg says "efi: EFI v2.00 by Lenovo" ** Affects: shim (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1925064 Title: shim(-signed)? does not boot on T420 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/shim/+bug/1925064/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs