GRUB menu not reflecting changes after kernel update

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Environment

SUSE Linux Enterprise Server 15
SUSE Linux Enterprise Server 12

Situation

Due to low free disk space, the contents of the /boot directory were copied to a new file system, and /etc/fstab was updated to mount the new file system to /boot.

After this change, the GRUB menu entries during system boot are not properly reflecting the newly installed kernels, even though the /boot/grub2/grub.cfg file is correctly updated.

Resolution

The issue can be resolved by reinstalling GRUB.

For detailed instructions on reinstalling the GRUB2 bootloader, refer to the GRUB2 bootloader reinstallation section in the following TID:
https://www.suse.com/support/kb/doc/?id=000019909

Cause

After moving the contents of /boot to a new file system, it is necessary to run grub2-install to update the GRUB prefix environment variable. This ensures GRUB can locate the modules and grub.cfg in the new file system. Failure to do so results in GRUB not fetching the updated boot information.

Additional Information

https://www.gnu.org/software/grub/manual/grub/html_node/prefix.html#prefix

Disclaimer

This Support Knowledgebase provides a valuable tool for SUSE customers and parties interested in our products and solutions to acquire information, ideas and learn from one another. Materials are provided for informational, personal or non-commercial use within your organization and are presented "AS IS" WITHOUT WARRANTY OF ANY KIND.