Attempting to change the photo in the ‘About Me’ Personal Settings control, I ran into the error above.
I found a good hint at http://forum.kde.org/viewtopic.php?f=63&t=62046#p134788 but with one minor change. I don’t know why they felt they needed to put the terminal command- you open ‘Configure Desktop’, go to the ‘Advanced’ tab and click ‘Login Manager’.
While they used ‘User, System’, that didn’t work for me- I had to choose ‘User’.