I installed trixie yesterday, using the netinst d-i image.
I selected task-xfce-desktop in tasksel.

At the end of the install I replaced systemd with sysvinit as per the
wiki instructions:
https://wiki.debian.org/Init#Changing_the_init_system_-_at_installation_time

Now, whenever I close the laptop lid, it tries to start a screen
locker.  But this doesn't work.  It puts up a dialogue box saying that

  Noen of the screen lock tools ran successfully,
  the screen will not be locked

I had to copy type this error message.

I suspect the problem is that no suitable screen lock tool is
installed, which is why I'm filing this bug against task-xfce-desktop.
I don't know where to look for logs.  I found .xsession-errors.
Nothing there looks very relevant but I have attached it anyway.

I'm about to completely replace my personal desktop configuration with
my longstanding dotfiles, and reconfigure everything, after which I
expect this bug no longer to affect me.  I'm reporting it because I
wanted to help other users.

Thanks for your attention.

Ian.

FTR, changing the power management settings for "On lid close" to
"Suspend" (in the power management settings from the XFCE tray battery
icon in the top right) resulted in successful suspend/resume.

So think probably the bug is that the intended screen locker/saver
isn't installed, or maybe that it's not wired up properly somehow.

Ian.