Ctrl+Alt+F1 stopped working in 16.04.LTS

Question

In older versions of Ubuntu I used to be able to get a character based login screen by pressing Ctrl + Alt+ f1 (or F2 or F3...).

After I upgraded to 16.04 LTS this no longer works. All I get when I press Ctrl + Alt+ f1 is a dark, blank screen. (Using Ctrl+Alt+f7 to switch back to the graphical user interface works.)

How can I fix this?

EDIT

I was trying to experiment with @sudodus' comment below, but before I got that far, I discovered some strange behaviour.

1. Sometimes I can get the consoles to work, but not always.
2. Sometimes the consoles display a login prompt, but do not accept any input.
3. Sometimes the computer locks completely when I press Ctrl+Alt+F1. (I can't event ssh to the computer from another computer.)

Perhaps what I really need is a fresh install... Sigh! :-(

EDIT

I just updated my computer from 4GB to 8GB of RAM. This solved the problem. (Confusing, I think; but I'm happy now.)

Solution

As indicated by the EDIT in my post, the problem was solved by increasing the amount of memory in the computer.

Comments

[sudodus]

It works for me in 16.04.1 LTS. Maybe there is some problem with the graphics. What happens if you boot with the boot option nomodeset, or with GRUB_TERMINAL=console via '/etc7default/grub' and 'sudo update-grub'. See this link: help.ubuntu.com/community/Grub2/Setup

[michael]

For reference, possibly a duplicate of (for example): askubuntu.com/questions/162535/… . It seems to work for me (for now) by setting both GRUB_TERMINAL=console and GRUB_GFXMODE=640x480

[michael]

see also (unrelated, but similar search terms might lead one to the wrong question) askubuntu.com/questions/979027/…