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Ubuntu 20.04 Keyboard and main display disabled after connecting 2nd monitor (?)

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Jakub Langr

Hello I have a strange problem I have not seen referenced anywhere else.

I have Ubuntu 20.04 (just updated, which thankfully recovered my 20.04 from an even worse state) and it works as expected except when I try to connect a 2nd monitor. Then the keyboard is not responsive and the original (laptop) display is disabled.

The strange thing is that I literally came home today, the laptop did not detect the 2nd display. After attempting some suggested "fixes" from SO and elsewhere, I managed to almost brick my laptop. But I have not changed anything significant prior to this change. It just honestly "happened". I then followed a fair few steps (incl. installing lightdm and installing different nvidia drivers) that were somewhat drastic.

The current state of the laptop is that I can work on the laptop screen just fine, but the second I connect my old monitor it goes into this odd state.

Few observations

  • It seems almost as if there's some context menu (but the screen is not shaded out or anything) I should accept somewhere else but even random key mashing (e.g. win+left/right) does not seem to solve the issue.
  • When I am in this mode I can press alt+ctrl+F4 and above and I get the old Ubuntu full-screen terminals. Maybe when I connect the screen, some screen manager crashes (gdm, lightdm?) and when I go into "fallback" it allows me to at least log in. But why is the keyboard only "connected" to the laptop screen (crashed?).
  • I have now figured out that alt+ctrl+F1 fairly reliably allows me to "reset" the UI and log back in. Sadly when the monitor is connected, I instantly get put into the "half-rendered" screen and the laptop one crashes again.
  • Happens indepenently of using nvidia or X drivers: drivers_choices

I feel like I'm out of depth and I would prefer to not brick my laptop. Do folks have any suggestions? That'd be much appreciated!

UPDATE: When I run: sleep 15 && xrandr -q and connect the external display, it provides no update (looks frozen). But when I disconnect the cable and login again (?), I get the following error: https://pastebin.com/pDDQqAi4 (truncated)

UPDATE 2: System logs were not at all informative. Only the "Applications" tab had anything even remotely relevant but still can't make heads or tails of that.enter image description here

Woud output of lspci -vv be helpful? Not sure what other diag information would help.

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Nate T avatar
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Nate T
Type `xrandr --auto` If that doesn't work, type `xrandr --output eDP-1 --left-of HDMI-1-1 --auto` Finally, you may need to use --right-of. That will get them working for now. You see all of those outputs on your pastebin? That is what I was referring to. g2g. good luck. btw your not going to brick your laptop with randr configs. I wouldn't sweat it.
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Jakub Langr
Bizarrely @nateT's `xrandr --auto` worked. I swear I used it a handful of times yesterday. But I plug in this morning run the command and it works... at least for now. Hope this suggestion helps someone else too!
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Nate T avatar
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Nate T
You still need the app below. The reason that your computer is having trouble with `x server` is because you have a `nvidia` graphics card. This is hardware. It cant be unloaded with a program. What you saw that was unloaded (the pic in your question) was the software interface for that hardware. The app that I recommended is the driver configuration settings for the hardware. It is made by `nvidia`, and provided as a way to make their hardware (your hardware) work properly with `X` (the software that `xrandr` is changing.) Updating my answer again. I'll try to explain more where possible.
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Nate T avatar Ubuntu
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Nate T

Try this:

From your terminal, run:

sudo apt install nvidia-settings

once the package installs, simply type nvidia-settings in the terminal to open the Nvidia X Server Settings app.

Inside the app, you will find multiple tabs / pages of configuration options specifically for systems running on a Nvidia gpu with multiple displays.

Take your time and configure all settings as you see fit, and as your particular setup requires. If you have been using xrandr to do your configurations until now, all of the options should be fairly straight-forward (honestly, the main configurations aren't that much different than the Display tab in the Ubuntu Settings app, apart from the fact that they work for Nvidia-based machines.)

Once you have carefully gone through all of the GUI menus inside the application, be sure to click 'Save' in the bottom right corner.

After you've saved, all that is left to do is to exit the application and reboot. This should set everything as it should be in order for both displays to work with the proper modes.

EDIT

I've gone ahead and included an image of the GUI to give you a visual reference in case there is anything that I've underexplained. It will also serve as an overview, as the GUI is simple enough that a snapshot could almost double as an instruction manual for anyone with minimal display config. experience.

Notice The resemblance to the main Ubuntu display Settings. enter image description here

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