Lubuntu 18.04.3 LTS on an Asus E402M laptop. Worked fine for years but after routine (using apt) patching beyond kernel 4.15.0-55-generic it now hangs on boot.
I suspected /boot/efi was being overfilled by a dual boot Windows installation so created a clean reinstall with sda1: a new 512M EFI partition with GRUB2 and sda2, a new Lubuntu 18.04.3. That should eliminate any Windows problems.
After a fresh install from ISO then apt-update && apt dist-upgrade I now have two kernels: 4.15.0-29-generic and 4.15.0-62-generic. 29 works perfectly. 62 hangs on boot.
62 in recovery mode gets started, installs the disk driver etc but hangs after installing the r8169 Gigabit ethernet driver. (The final message on screen is "Can't disable ASPM"). I cannot find any logs of this. (e.g. journalctl --list-boots has all the successful 0-29 boot logs, and no mention at all of failed 0-62 boots. I have configured journalctl to persist logs but no good).
Can anyone help me find log files to diagnose the problem further? (this feels like a basic thing I am missing!)
Is it worth rolling back to the r8168 ethernet driver instead of r8169, or is that a red herring? I have downloaded a r8168 .deb but am reluctant to tinker before I have located the problem. r8169 seems to work fine in kernel 19.
I believe all kernels up to (ubuntu label) 55 work fine, and none of the newer ones do. Does that fact help diagnosis?
Very grateful any help -- I'd be delighted to post some diagnostics if someone can answer Q1 and suggest where to look!