After reading into some of recent topics I got the feeling, that your nvidia card got unsupported by nvidia, and newer Ubuntu does not package correct driver.
But you did an inplace upgrade, and the open-source nouveau driver is left blacklisted, that’s why the kernel won’t load it. The proprietary drivers -I guess- are incompatible with you current kernel, that’s why it won’t be loaded.
Can you try to remove nouveu blacklist from /etc/modprobe.d/ ?
Or, install a patched driver for your videocard.
See my post in the other topic How to add a kernel module - #3 by kovacslt