I upgraded through the Software prompt from 16.04 LTS to 18.04 LTS. Everything went well until near the end when there were a bunch of lib* failures. It said the update failed and the system could be unstable. Sure enough it upgraded to 18.04 but had a login loop. I managed to solve that somehow (I've been using the xorg driver with no Nvidia drivers installed anyway). Now it won't boot on kernel 4.15 at all. It does work on 4.13 and some earlier ones but it is not functioning properly. My LAMP server has not restarted. My wireless USB is worked at first but now is staying green no matter what so I'm using a LAN. I've tried updating, upgrading but there is nothing to do. I've tried the suggested DIST upgrade from other posts - nothing. Is there anything to do to make it stable or is a clean install the only real fix? P.S. I've never had a successful upgrade with Ubuntu and I'm a long-time user. I always wind up with a new install it seems. I've got a an HP Pavilion. 2GB AMD Athlon 64x2 64 bit.
I was unable to resolve this so I attempted a fresh install of 18.04. On multiple attempts it gave me a failure to install grub on /sda and I was never able to get the grub to install anywhere. So I reinstalled 16.04, updated at the terminal using sudo update-manager -c
It updated to the latest kernel, restarted, and then I did it again to get the 18.04 upgrade.
This finished successfully. My Belkin wireless USB works. Now I will begin restoring my files and installing the LAMP server to get my site back on line. This has taken be all day and all evening of a Saturday. There's no excuse for this. If it is going to give me a host of failures at the end, why can't it check before it installs to prevent it from installing? Thanks for all who attempted to help.