No signal for the second monitor


My second monitor is not detected on Ubuntu 21.10 although everything was okay 2-3 days ago.

  • I have tried to reinstall “nvidia-driver-470” as recommended in the output of ubuntu-drivers devices
sudo prime-select nvidia
sudo rm /etc/modprobe.d/blacklist-nvidia.conf /lib/modprobe.d/blacklist-nvidia.conf
sudo update-initramfs -u
  • I’ve also tried removing blacklist files(there were none.)

  • I also modified /lib/modprobe.d/nvidia-kms.conf file and changed 1 to 0.

Here is my bug report.
nvidia-bug-report.log.gz (371.4 KB)

Any advice on how to resolve that issue? Thanks in advance.

Your nvidia gpu is added as “3D device” which might point to it having no outputs at all. Your intel igpu also reports no other outputs than the internal display. I suspect a kernel bug in the i915 driver, can you return to a previous kernel in grub menu?

After you said it might be related to a kernel bug, I checked which kernel has been used last time the external monitor worked fine, it was my current kernel “linux-image-5.13.0-21-generic”. Anyhow, I switched back to “linux-image-5.13.0-20-generic” and it worked just fine. To try again, I switched back to a newer kernel, and it is working properly mysteriously. :) Thank you for your interest. You’re a life-saver.