During the default installation, the space allocated by proxmox to /boot is less than 300M. The iteration of proxmox is very fast, and /boot can easily be filled up. If you are not careful, the upgrade will fail. The only way is to manually delete the old kernel.

Delete old kernel

proxmox is based on debian. Every time you use apt update && apt dist-upgrade, debian’s linux-image and pve-kernel will be automatically installed. These two items will occupy the space of /boot, so to make space, delete these two old kernel.

• Copy and use kernel
• Find old kernel
• Delete it NOTE: If the upgrade of proxmox fails due to insufficient space in /boot, update-grub will also fail, but don’t worry, every time you use the old apt purge kernel, update-grub will be reinstalled. Naturally, the latest kernel will be the preferred startup option. If you are not sure, you can use grub-set-default $menuentry_id and grub-reboot $menuentry_id to manually set the default kernel for the next startup. The above steps are still a bit troublesome, and I have to think about /boot from time to time. Fortunately, there are two lazy methods:

2. When installing proxmox, manually set the /boot partition to 2G, which will at least keep it clean for a while.

Reference article

uname -mrs

dpkg --list | grep "linux-image"
dpkg --list | grep "pve-kernel"

apt purge linux-image-$old_version