Ubuntu 18.04 boots to black screen without nvidia, tried lightdm, xfce, but nothing worked

Question

I upgraded from Ubuntu 17.10 to 18.04 and everything was fine for about 2 moths after the upgrade.

Now, my system boots to a black screen (the monitor backlight keeps on), and I can only reach the login screen after about 5 minutes.

Curiously, if I keep pressing the key "E" repeatedly during boot, it boots normally and quickly.

I've removed "quiet splash" from /etc/default/boot and sudp update-grub2, but I don't see any errors among those commands. It quickly goes to a full black screen.

I've tried sudo apt-get install lightdm sudo apt-get install xfce sudo dpkg-reconfigure gdm3 sudo dpkg-reconfigure lightdm

(not in that specific order... those are just the commands i've already tried).

I don't use nvidia video card.

The output from dmesg | less > dmesg.txt

can be downloaded from my google drive, the link below, if the forum allows: https://drive.google.com/open?id=1aj9n4ovguhZ4ewJCbQ_FR9jRJEjd8t18

This is my workstation and I can't format it.

I would appreciate any help.

Thank you! Thiago Garcia.

Answer 1

[SOLVED] On 2018-July-25, an update asked me if i wanted to keep my old grub configuration file or use the one from the update. I said I wanted to update, and the problem was fixed. – Thiago Garcia 1 hour ago
lists.ubuntu.com/archives/ubuntu-security-announce/2018-July/… Summary: A regression that caused boot failures was fixed in the Linux kernel. Details: USN-3695-1 fixed vulnerabilities in the Linux kernel for Ubuntu 18.04 LTS. Unfortunately, the fix for CVE-2018-1108 introduced a regression where insufficient early entropy prevented services from starting, leading in some situations to a failure to boot, This update addresses the issue.