Ubuntu 18.04 External monitor stopped working

Hey there.

I’m using Ubuntu 18.04 and my external monitor was working as expected. I’m not sure what changed since my previous reboot (can’t recall what updates were last installed and when), but now all of a sudden the external monitor is not detected anymore., all I get is a “No video input” message. I’ve tried multiple monitors and HDMI cables.

I’m on driver version 435 and the kernel module seems to be loaded fine:

dmesg | grep nvidia
[    3.933028] nvidia: loading out-of-tree module taints kernel.
[    3.933035] nvidia: module license 'NVIDIA' taints kernel.
[    3.971264] nvidia-nvlink: Nvlink Core is being initialized, major device number 234
[    3.972752] nvidia 0000:02:00.0: enabling device (0006 -> 0007)
[    4.124046] nvidia-modeset: Loading NVIDIA Kernel Mode Setting Driver for UNIX platforms  435.21  Sun Aug 25 08:07:52 CDT 2019
[    4.152036] [drm] [nvidia-drm] [GPU ID 0x00000200] Loading driver
[    4.569474] [drm] Initialized nvidia-drm 0.0.0 20160202 for 0000:02:00.0 on minor 1
[    4.679779] nvidia-uvm: Loaded the UVM driver, major device number 510.

I have secure boot disabled and have tried every suggestion I could find online (disabling modesetting, installing lightdm, booting a different kernel, changing to open source drivers, etc) with no success.

Can you please review the attached bug report and suggest what else I can try?

Thanks!

EDIT: I have also just tried upgrading to driver version 440 from the PPA, with the same results.
nvidia-bug-report.log.gz (1.18 MB)

Seems to be some incompatible kernel change. Please try this:
https://devtalk.nvidia.com/default/topic/1066683/linux/ubuntu-18-04-3-blank-screen-at-startup-with-430-drivers-and-gtx-960/post/5402308/#5402308
Leads to tearing, though.

Hi generix, thank you for the answer.

As I tried to explain, I had already tried disabling modesetting, unsuccessfully.

Any other suggestions are greatly appreciated.

Taken a deeper look at the log at it seems that all external outputs are connected to the intel gpu anyway so the nvidia driver shouldn’t have any influence on their function. Does it work when you switch to intel?
Did you have any external monitor connected while you created the logs? Did you try moving the connector a bit while plugged or try connecting the monitor to the DP connector in case the hdmi slot is broken