Thank you Joseph, the upstream kernel from months ago was the cause of the issue. I had completely forgotten about it being there and did not recognise the change in version numbering as significant.
The steps I performed were:
> If compiled and installed via make install, you will need to manually remove the following entries:
>
> /boot/vmlinuz*KERNEL-VERSION*
> /boot/initrd*KERNEL-VERSION*
> /boot/System-map*KERNEL-VERSION*
> /boot/config-*KERNEL-VERSION*
> /lib/modules/*KERNEL-VERSION*/
> /var/lib/initramfs/*KERNEL-VERSION*/
Thank you Joseph, the upstream kernel from months ago was the cause of the issue. I had completely forgotten about it being there and did not recognise the change in version numbering as significant.
I followed the steps outlined in http:// askubuntu. com/a/594484/ 109072 to remove the kernel and a reboot now comepletes cleanly.
The steps I performed were: KERNEL- VERSION* KERNEL- VERSION* map*KERNEL- VERSION* *KERNEL- VERSION* *KERNEL- VERSION* / initramfs/ *KERNEL- VERSION* /
> If compiled and installed via make install, you will need to manually remove the following entries:
>
> /boot/vmlinuz*
> /boot/initrd*
> /boot/System-
> /boot/config-
> /lib/modules/
> /var/lib/
Where KERNEL-VERSION for me was 4.4.21*.