"The proof of the pudding is in the eating" I reverted the change, so that said line once again reads #GRUB_TIMEOUT_STYLE=hidden , nothing else but sudo update-grub, which did find the W10 partition:
$ sudo update-grub [sudo] password for udippel: Sourcing file `/etc/default/grub' Generating grub configuration file ... Found linux image: /boot/vmlinuz-6.8.0-44-generic Found initrd image: /boot/initrd.img-6.8.0-44-generic Found linux image: /boot/vmlinuz-6.8.0-41-generic Found initrd image: /boot/initrd.img-6.8.0-41-generic Found memtest86+x64 image: /memtest86+x64.bin Warning: os-prober will be executed to detect other bootable partitions. Its output will be used to detect bootable binaries on them and create new boot entries. Found Windows 10 on /dev/sda1 Adding boot menu entry for UEFI Firmware Settings ... done Rebooted, and once again no grub menu. $ dpkg -l | grep grub ii grub-common 2.12-1ubuntu7 amd64 GRand Unified Bootloader (common files) ii grub-gfxpayload-lists 0.7build2 amd64 GRUB gfxpayload blacklist ii grub-pc 2.12-1ubuntu7 amd64 GRand Unified Bootloader, version 2 (PC/BIOS version) ii grub-pc-bin 2.12-1ubuntu7 amd64 GRand Unified Bootloader, version 2 (PC/BIOS modules) ii grub-theme-breeze 5.27.11-0ubuntu2 amd64 Breeze theme for GRUB 2 ii grub2-common 2.12-1ubuntu7 amd64 GRand Unified Bootloader (common files for version 2) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2080785 Title: Wrong defaults after (deprecated) changes: #GRUB_TIMEOUT_STYLE To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/2080785/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs