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After installing an update proposed by Ubuntu 20.04 and having carried out the proposed reboot, I can no longer complete the boot, the system comes up to the moment of starting the graphical interface and then remains stationary showing only an underscore in the bottom corner top left. Sometimes after a while it seems to go on and everything goes black. In both cases, even waiting a lot, nothing happens anymore and I have to switch off by forcing. If I enter recovery mode I can enter command mode (but without network, I cannot start it).

enter image description here

Leandro De Persiis
  • 101

3 Answers3

6

I solved!

I went into recovery mode again. I managed to activate the network by following the instructions of this: https://core.docs.ubuntu.com/en/stacks/network/network-manager/docs/configure-wifi-connections and other solutions on askubuntu regarding access to the network in command mode (this: Ubuntu Resolving Host & Wifi Problem). In particular the command:

dhclient -v wlan0

Replacing wlan0 with the name of our device (mine was wlp3s0 for example)

At this point, having the network I could run:

sudo apt-get update

then I ran:

sudo apt-get install --reinstall ubuntu-desktop

(as indicated here: Boot stuck - how to start GUI from the command line?) and finally:

reboot

It took a while to complete the final part of the boot, but it finally went!

Leandro De Persiis
  • 101
2

I faced the same problem of black screen at boot (the GUI could not start) just after having applied the Ubuntu 20.04 LTS updates.

=> i could authenticate (using ctrl+alt+F2) and submit those commands in order to investigate :

sudo apt update
sudo apt reinstall '~i'

after 15 to 30 minutes of execution time it failed ; the error was related to nvidia-340

attached : photo of the screen with the apt reinstall all command error message

therefore i decided to remove the proprietary GPU drivers (from nvidia) and replace them by the generic driver :

sudo  systemctl  stop  lightdm.service

sudo  apt  purge  '^nvidia-*'


sudo  apt  install  xserver-xorg-video-nouveau


sudo  reboot  now

...and it solved the issue !

PS (10/01/2021) : to confirm what happened on my father's computer with NVIDIA-340 I've just found this where they explain that this legacy driver is no longer supported by Nvidia, and this. I believe that it is safer now to use "xserver-xorg-video-nouveau" if you run Ubuntu 20.04 or later with this GPU.

Gilles Gaido
  • 173
2

I had the same issue after updating my nvidia graphics driver.

A work-around is to restart gdm3 manually:

ctrl-alt-F3

sudo systemctl restart gdm3

I believe a long term solution is to purge and reinstall gdm3 (likely the nvidia driver install broken some gdm3 dependency package?).

sugab
  • 4,367
Jimmy Pettersson
  • 121