Updated: 28 September 2026 · Applies to: AlmaLinux 9, Rocky Linux 9, Ubuntu 24.04 and Debian 12
"At least 250MB more space needed on the /boot filesystem" means the /boot partition is full of old kernels, so a new kernel cannot be installed.
Check
df -h /boot rpm -q kernel # AlmaLinux / Rocky dpkg -l 'linux-image*' # Ubuntu / Debian
Remove old kernels (root)
dnf remove --oldinstallonly --setopt installonly_limit=2 kernel # AlmaLinux / Rocky apt autoremove --purge # Ubuntu / Debian
Keep at least the running kernel (uname -r) and one previous one. Then run the update again.
