I use Ubuntu on an old spare computer, mostly as a low-capability backup in case my usual computer is inaccessible (updates, etc). I had been using Ubuntu 18, but a software update caused a number of strange issues.

I decided that it would be simpler to recover the small number of important files and update to the newest version, 19.04, rather than trying to fix the problem. I installed from a USB LiveCD with no apparent issues, and booted in normally. The automatic software updater suggested some updates, and I agreed.

When I rebooted the system, at the software updater's request, it would not progress past the screen with the Ubuntu logo and the five orange/white dots. The dots would cycle indefinitely, but showed no indication of progressing. I could not use the keyboard at this time; Attempting to press F12 would not open up the terminal that displays the ongoing processes, and CTRL + ALT + F3 or etc would not change to a separate TTY. However, I successfully managed to reboot using Alt + Sysrq + REISUB, meaning the keyboard was apparently recognized in some capacity.

After some experimentation, I discovered that there is a period shortly after the loading screen appears where I can press F12 and have it take me to the console that shows the boot processes. To my surprise, after a few seconds, the login screen appeared, and I logged in with no issue.

After some testing, I have determined that if I leave the computer to boot normally, it will consistently hang on the screen, but if I change to the console before the keyboard is ignored, it will consistently succeed in loading the OS. I would like to know why this is, and ideally how I might be able to fix it.

First update: I attempted to start the OS "normally", and after some time pressed F12. This time, it brought me to the terminal, with a message A start job is running for Hold until boot process finishes up (Xmin Xs/no limit) at the bottom of the list. I have seen this message a few times; It was something that occurred even before I installed the new version. Looking up this phrase has yielded some questions on various sites, but I have not been able to use their answers in my case.

When I tried to reboot and reach the login screen by pressing F12 near the beginning, as before, it did not succeed; Evidently I had not been fast enough. My keypresses would not be accepted.

A third login attempt allowed me to get in by pressing F12 early.

Here are the logs for each of these attempts, respectively:
The "Hold" boot
The "Hang at splash" boot
The successful boot

Second update: After my previous successful login (where I managed to get in by hitting F12), the computer took an excessive amount of time to shut down. I ultimately ended up forcing the power off by holding the power button. I suspect this is related.

  • journalctl will show you what was happening during successful boot. Then enable previous boot recordings and use journalctl -b-1 to display previous failed boot. – WinEunuuchs2Unix Oct 8 '19 at 1:37
  • @WinEunuuchs2Unix I have found at least one erroneous boot log, however there are over 3000 lines and I do not know what to look for here. I can see a number of events pertaining to my keypresses, disconnect and reconnect of the mouse and keyboard, confirming this to be one of the boots that did not succeed. – MutantOctopus Oct 8 '19 at 2:07
  • Believe me I know how difficult it is studying boot logs and error messages. I've spend hours on many days. Unfortunately sometimes it is the only way. With luck though someone has experienced the exact same problem and posts a perfect answer for you. – WinEunuuchs2Unix Oct 8 '19 at 2:12
  • The "hold boot" shows unusual lines right off the bat: "gran_size: 64K chunk_size: 64K num_reg: 8 lose cover RAM: 60G" This is repeated many times. – WinEunuuchs2Unix Oct 8 '19 at 2:58
  • This appears to be consistent across all the logs. What is unusual about this? – MutantOctopus Oct 8 '19 at 3:02

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