Every time I select the Compositor setting in Display Configuration -- System Settings, the system setting app crashes.
https://kaosx.us/docs Post relevant info so anyone willing to help you as something useful to go by.
Seems to be a known bug https://bugs.kde.org/show_bug.cgi?id=412998#c9
I think it's corrected in KDE 5.17.2, since I don't have the problem with another distro using this latter version.
Sorry for the lack of info. I'm not savvy on locating the relevant error files, etc.
Please read the link provided for you, it is just a few clicks to provide needed info, posting here then refusing to read makes no sense....