Thank you for the answer. The problem was I accidentally removed the */boot *folder, WHILE trying to back it up. So there were only *OS folders *and something was missing.
I figured out later that *kernels are also stored in /boot *and tried to reinstall the kernel manually, but ran into a number of minor problems. Though I also found out that *Timeshift* keeps not only /root but also /boot folder (even if it is physically on the other disk)! Thanks Universe So I just copied files from the timeshift /boot backup to the new *ESP* folder and *GRUB *showed the OS correctly. There were also some minor problems which I solved with *apt update/upgrade* while being in *chroot*. So, *the problem is solved*. At least it looks like that for now, as everything works fine i guess. But i must mention that *this passage from Debian Wiki seems incorrect* > > Bind mount various virtual filesystems: # for i in /dev /dev/pts /proc /sys /sys/firmware/efi/efivars /run; do > mount -B $i /mnt/$i; done https://wiki.debian.org/GrubEFIReinstall#Using_the_rEFInd_rescue_media *I had to use* sudo mount --bind /dev /mnt/dev > sudo mount --bind /dev/pts /mnt/dev/pts > sudo mount --bind /sys /mnt/sys > sudo mount --bind /proc /mnt/proc > sudo mount --bind /sys/firmware/efi/efivars /mnt/sys/firmware/efi/efivars And* copy /etc/resolv.conf to mounted disk*, to make the internet work under *chroot*. I will try to suggest an update in the Debian Wiki, if it is possible for a newcomer there. пт, 21 мар. 2025 г. в 05:58, Max Nikulin <maniku...@gmail.com>: > On 20/03/2025 03:22, J wrote: > > > > But before this oopsie deletion I have saved as a back-up at least > > something from /boot folder, or maybe even everything. > > Copy files from backup to /boot and to the EFI system partition > > EFI/debian/BOOTX64.CSV > EFI/debian/fbx64.efi > EFI/debian/grub.cfg > EFI/debian/grubx64.efi > EFI/debian/mmx64.efi > EFI/debian/shimx64.efi > > Check if a boot entry pointing to \EFI\debian\shimx64.efi exists in UEFI > NVRAM > > efibootmgr -v > > and create it otherwise. UEFI (BIOS) may have an option to boot from a > specified .efi file and it may be an alternative for recovery. > > > 1) I have created a new ESP partition (on the other disc), so that to > > make it different from Windows boot drive. BTW, is it OK to have two > > partitions with ESP and boot flags..? > > It depends on UEFI implementation. If you have separate disks for > Windows and for Debian then I find it reasonable to have independent EFI > partitions on each drive. Just ensure that the boot entry points to the > proper partition. As first step to boot installed Debian I would restore > EFI/debian to the existing partition. > > Perhaps you may find some hints on the wiki page > https://wiki.debian.org/UEFI > >
