This has been noted in the Ubuntu builds for a while (2+ years) but I don't see it as a KDE bugreport, so I'm putting it in now, in the hope that it can be resolved. Symptom: Attempting to start multiple instances of k3b using the --nofork option gets the following error mesage: $ k3b --nofork --device /dev/sr0 QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave. unnamed app(16946): KUniqueApplication: Can't setup D-Bus service. Probably already running. Repeatability: 100%, I've been experiencing this since Ubuntu 12.04 (possibly before then, as I didn't have multiple DVD writers installed) Reproducible: Always Steps to Reproduce: 1. start an instance of "k3b --nofork" 2. start a second instance "k3b --nofork" Actual Results: QDBusConnection: session D-Bus connection created before QCoreApplication. Application may misbehave. unnamed app(16946): KUniqueApplication: Can't setup D-Bus service. Probably already running. Expected Results: A second instance should start.
Actually what nofork does is not forking the process, and that works pretty well, creating two different instances is some other code. Why do you need to run two instances of k3b?
"Why do you need to run two instances of k3b?" Multiple burners. Unless you've changed the way it handles that.
So --nofork is not the problem, the problem is you can't start two processes, ok.
--nofork USED to be the documented way of starting multiple k3b processes. It's been removed without any explanation other than "some users were inadvertently starting the program twice" - which is odd, because without --nofork, a second instance won't start.
See https://forum.kde.org/viewtopic.php?f=19&t=91386