Ben Saylor wrote: [...]
I don't get any new messages in ~/.xsession-errors after an unsuccessful logout attempt. However, the problem seems to occur if and only if qjackctl is running, so I think I've found the culprit. As a workaround, I'll just quit qjackctl before logging out. But it still seems like a problem with KDE that an application can cause logout to fail silently. Thanks for the suggestions!
One more suggestion: Maybe you can at least automate this workaround by
putting a script in ~/.kde/shutdown which will kill qjackctl for you.
(You can simply create the directory if you do not have it already.) In
the script a simple "pkill qjackctl" or "pkill -signal 9 qjackctl" might
do the trick for you. This might not work, however, if KDE already hangs
before it reaches the stage in which it runs the shutdown scripts.
Regards,
Florian