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I've been running Ubuntu 18.04 in Virtualbox on a Windows 10 Dell XPS laptop. I decided to upgrade to Ubuntu 20.04. The upgrade went OK, but when I start the virtual image I get a purple screen with no login prompt. I can't do anything from there. I have tried to send a CTRL-ALT-F1 signal to get a console, but that got no response. Either Ubuntu didn't respond or the Virtualbox host key no longer defaults to the CTRL-ALT sequence. Weirdly, I have had a login on the Ubuntu 20.04 image, but I can't remember how I tricked it into that. Any ideas?

cj_rupp
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  • To switch screens in VB use right CTRL-F1 then right CTRL-F7 The only VM I have to do this with is a 20.04 Ubuntu MATE. Reference: https://askubuntu.com/a/948497/243321 – Organic Marble Apr 27 '20 at 16:48
  • I worked out how to lock the function keys on the Dell XPS 13. So I could be sure that the function key sequence was being sent. Host-F1 did nothing, Host-F2 switched to a console view, but with no login prompt. Host-F7 did not switch back to the graphical view. Host-Delete rebooted Ubuntu. After a while this behaviour got lost again, perhaps I confused it. I'll keep on plugging away, but it does seem that something is wrong in the Ubuntu image. – cj_rupp Apr 28 '20 at 08:52
  • I did eventually get a login prompt from there I tried a few things to get grub2 to raise a splash login window. Nothing worked. It was getting complicated, so I tried to follow the boot-repair instructions. Now I get a grub prompt when I try to reboot. I think this image is probably dead from here on in? Any ideas about resuscitation? – cj_rupp Apr 28 '20 at 14:29

3 Answers3

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I generated a new image for Ubuntu 20.04 from the .iso release. So the situation has resolved itself. But, there's still a number of things I don't know. I don't know if trying to update a virtual image was wrong in itself. I don't know if grub was failing to raise the login window, or if one of the customisations I had made, in the usual manner, was causing the login (splash screen?) to block. I hope I don't stumble on something with the new image, but so far so good. Some experience, but not very much learning.

cj_rupp
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I had the same problem, remove Guest Additions fixed for me:

  • boot in recovery mode and login on root shell
  • disable GUI on boot ( systemctl set-default multi-user.target )
  • reboot and login with my regular user at prompt
  • manually start GUI (startx)
  • uninstall VBOX Guest Additions from mounted virtual CD (VBoxLinuxAdditions.run uninstall)
  • enable GUI on boot (sudo systemctl set-default graphical.target)
  • reboot
massimo morselli
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  • Thanks for the information. I didn't know about the systemctl commands. Unfortunately I can't test this because I destroyed the old image. It might have been Guest Additions, but I wouldn't want to work without them in the long run, because they scale the screen correctly. – cj_rupp May 04 '20 at 18:33
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I had the same problem. Fortunately, I could remotely login to the system (as everything worked).

So, to solve the issue I opened the /etc/default/grub with a text editor and changed the:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

to

 GRUB_CMDLINE_LINUX_DEFAULT="text quiet"

Next, the grub should have been updated with the following command:

sudo update-grub

After reboot, the login prompt re-appeared - again. Hope it helps.

(Ps. Interestingly, it happened with me two years ago when I upgraded from 16.04 to 18.04...)

aszoke
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