Dear forum readers,

I am trying to hunt down a problem with kscreenlocker. Whenever the locker needs to kick in (after resume, inactivity or explicitly by pressing the shortcut CTL-ALT-L),
something grabs the input focus, but no screenlock shows up. I need to kill the session at this point. After some research in bug reports, I tried to invoke the screenlocker 'by hand'. In this way I see a segfault, due to a missing 'module'

sts@nbof16:~$ /usr/lib/x86_64-linux-gnu/libexec/kscreenlocker_greet --testing
"file:///usr/share/plasma/look-and-feel/org.kde.breeze.desktop/contents/lockscreen/LockScreen.qml"
"Error loading QML file.\n25: module \"org.kde.kscreenlocker\" is not installed\n"
Failed to load lockscreen QML, falling back to built-in locker
"qrc:/fallbacktheme/LockScreen.qml"
"Error loading QML file.\n25: module \"org.kde.plasma.private.sessions\" is not installed\n"
KCrash: crashing... crashRecursionCounter = 2
KCrash: Application Name = kscreenlocker_greet path = /usr/lib/x86_64-linux-gnu/libexec pid = 28693
KCrash: Arguments: /usr/lib/x86_64-linux-gnu/libexec/kscreenlocker_greet --testing
Segmentation fault

I got here by an install of debian-testing (kde-full on a lenovo t460p laptop). dpkg -S and aptitude search do not
point me anywhere. Does anybody here know what I need to install to provide the missing piece of software?

Thanks a lot

Stefan