No login screen when waking from sleep

[Raphael Mankin]

This is similar to, but not identical to #1374830.

I am running a Lenovo P1 with an external monitor. Generally the laptop lid is closed and I am relying just on an external monitor, mouse and keyboard.

*Sometimes*, when waking the machine from sleep either:
a. It does not wake the external monitor at all, or
b1. It wakes the external monitor, but all I get is a mouse cursor on a black screen. Letting it time out and invoke the screensaver then enables me to login, or
b2. As b1, but the screensaver does not start. I then have to open and shut the laptop lid in order to wake the external monitor properly.

This whole behaviour is more common when the sleep has been of long duration, e.g. overnight.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: xfce4-power-manager 1.6.6-1
ProcVersionSignature: Ubuntu 5.4.0-42.46-generic 5.4.44
Uname: Linux 5.4.0-42-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu27.6
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: XFCE
Date: Sun Aug 23 10:44:58 2020
InstallationDate: Installed on 2020-08-09 (13 days ago)
InstallationMedia: Xubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
SourcePackage: xfce4-power-manager
UpgradeStatus: No upgrade log present (probably fresh install)

[Raphael Mankin (raph-p)]

More screenshots

[Raphael Mankin (raph-p)]

Some more info:

This bug affected me on a clean install of Ubuntu 20.04.

On upgrading another machine from 18.04 to 20.04 I found that I had both xscreensaver and xfce4-screensaver installed. This caused me to have to do a double unlock each time I wanted to wake the PC. I therefore deleted xscreensaver and got the same problem as on the clean installation, only worse. On the clean installation I could type the unlock password even though unlock-widget was not visible; on the upgraded machine I could not unlock at all.

I therefore removed xfce4-screensaver and re-installed xscreensaver. This fixed the problem. I now have two usable systems.