Can not switch to virtual console (TTY)

[Jarno Suni]

If I try to switch to a virtual console by Ctrl-Alt-F1 or greater (up to Ctrl-Alt-F6), screen is black. But I can return by Ctrl-Alt-F7 (if light-locker is not used; update: now I can return even if light-locker is used).
This happens with nvidia-340 driver (I am using version 340.107-0ubuntu0.18.04.1 from bionic-updates), but not with nouveau driver. With nouveau driver I can switch to TTY2, TTY3 and TTY6 for text console, and TTY7 gives the X session.

This bug also breaks light-locker, switching user and maybe something else.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: light-locker 1.8.0-1ubuntu1
ProcVersionSignature: Ubuntu 4.18.0-13.14~18.04.1-generic 4.18.17
Uname: Linux 4.18.0-13-generic x86_64
NonfreeKernelModules: wl nvidia
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CurrentDesktop: XFCE
Date: Fri Jan 11 16:17:15 2019
EcryptfsInUse: Yes
InstallationDate: Installed on 2017-01-05 (735 days ago)
InstallationMedia: Xubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
SourcePackage: light-locker
UpgradeStatus: No upgrade log present (probably fresh install)

[Theo Linkspfeifer (lastonestanding)]

According to your bug description, this it not a bug in light-locker.

Is it a new problem that appeared after a kernel or nvidia driver update?

[Jarno Suni (jarnos)]

If I switch from nvidia-340 to nouveau driver, the problem disappears.

[Theo Linkspfeifer (lastonestanding)]

Maybe related to bug 1760068.

[Jarno Suni (jarnos)]

I reported this by nvidia-bug-report.sh

[Jarno Suni (jarnos)]

Does not work with 340.107-0ubuntu0.18.04.2 either. HW: Geforce 9400M.

I do not know, if related, but with different hardware and 340.107-0ubuntu0.16.04.2 in Xenial I can switch to TTY: On a laptop with a monitor connected to HDMI, the TTY is seen in integrated display only even if the X session is seen on the HDMI monitor. On a (Xenial) PC with a VGA monitor connected TTY is shown in the monitor.

[Jarno Suni (jarnos)]

My 18.04 upgrade was somewhat corrupted. I had to do some manual troubleshooting first to make the upgrade complete. I do not know, if it is still complete, but this bug exists anyway.