Hi,
Why does my server keep booting into an older kernel, even though I’ve set the latest version as the default and it appears in the GRUB menu?
The latest kernel version is set as the default boot option and appears in the GRUB menu.
Any help highly appreciated.
Hi,
Back up the current BLS configuration files by moving them to a backup directory.
# mkdir /boot/loader/backup
# mv /boot/loader/entries/* /boot/loader/backup/
Re-create BLS configuration files:
# for i in `rpm -q kernel | sed 's/kernel-//g' | sort | xargs echo` ; do kernel-install add $i /lib/modules/$i/vmlinuz ; done
Recreate the GRUB configuration file.
For BIOS;
# grub2-mkconfig -o /boot/grub2/grub.cfg
For EFI;
# grub2-mkconfig -o /boot/efi/EFI/redhat/grub.cfg
In case you have AlmaLinux 9.3 or later;
# grub2-mkconfig -o /boot/grub2/grub.cfg
Recreate the GRUB configuration file. On UEFI systems, the /boot/efi/EFI/redhat/grub.cfg file GRUB used before is now just a stub pointing to /boot/grub2/grub.cfg, which holds the actual configuration. In RHEL 9, avoid using grub2-mkconfig with /boot/efi/EFI/redhat/grub.cfg as the output.
The problem stems from a mismatch between the system’s updated machine-id and GRUB’s Boot Loader Specification (BLS) sorting mechanism.
Identifier Conflict: The /etc/machine-id file prefixes filenames in /boot/loader/entries/. When machine-id changes, new kernels use the updated ID, but older kernel entries retain the previous ID.
Sorting Priority: GRUB’s blscfg module sorts boot entries in reverse-alphanumeric order based on these filenames. Since filenames start with machine-id, it becomes the primary sorting key.
Old ID Wins: If the previous machine-id sorts higher alphanumerically (like “z…” before “a…”), older kernel entries appear first in the boot menu.
Default Behavior: With GRUB_DEFAULT=0 in /etc/default/grub, the system boots the first entry (index 0), which is the older kernel due to sorting precedence over version numbers.
Richard.