Screen locking issue - No lock on start-up

[Rudolf Metzler]

After the recent software updates, the system doesn't lock the screen after the regular start-up procedure. So there is no demand for a password and my system is open for everyone although i set a password

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: gnome-screensaver 3.6.1-7ubuntu4
ProcVersionSignature: Ubuntu 4.15.0-47.50~16.04.1-generic 4.15.18
Uname: Linux 4.15.0-47-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.1-0ubuntu2.18
Architecture: amd64
CurrentDesktop: Unity
Date: Tue Apr 2 20:47:21 2019
GnomeSessionIdleInhibited: No
GnomeSessionInhibitors: None
GsettingsGnomeSession:
 org.gnome.desktop.session session-name 'ubuntu'
 org.gnome.desktop.session idle-delay uint32 0
InstallationDate: Installed on 2017-03-15 (747 days ago)
InstallationMedia: Ubuntu 16.04.2 LTS "Xenial Xerus" - Release amd64 (20170215.2)
SourcePackage: gnome-screensaver
Symptom: security
Title: Screen locking issue
UpgradeStatus: No upgrade log present (probably fresh install)