We have discovered a bug (or missing feature) when upgrading kernels.
When you have upgraded a kernel the triggers are not executed in a
proper order so the initramfs image is not there to be detected by the
This causes extlinux.conf to not include the needed initrd= option and
the kernel will not boot.
Before you reboot, please verify that your /boot/extlinux.conf has the
needed initrd= option. If not you can try run update-extlinux manually
as a temp workaround.