Attaching to a process and then killing it causes a stacktrace in both the UI and on the command line: Exception in thread "main" java.lang.RuntimeException: {frysk.proc.live.LinuxPtraceTask@5b21755f,pid=19574,tid=19574,state=destroyed} in state "destroyed" did not handle handleStoppedEvent SIGSTOP(19) at frysk.proc.live.State.unhandled(State.java:67) at frysk.proc.live.LinuxPtraceTaskState.handleStoppedEvent(LinuxPtraceTaskState.java:71) at frysk.proc.live.LinuxPtraceTask.processStoppedEvent(LinuxPtraceTask.java:226) at frysk.proc.live.LinuxWaitBuilder.stopped(LinuxWaitBuilder.java:202) at frysk.sys.Wait.wait(Wait.cxx:586) at frysk.sys.Wait.wait(Wait.java:126) at frysk.event.WaitEventLoop.block(WaitEventLoop.java:81) at frysk.event.EventLoop.runEventLoop(EventLoop.java:372) at frysk.event.EventLoop.run(EventLoop.java:482) at frysk.bindir.fhpd.main(fhpd.java:186) and here is the stack trace from the UI: {frysk.proc.live.LinuxPtraceProc@665bad3e,pid=20304,state=running} in state "running" did not handle handleRemoval java.lang.RuntimeException: {frysk.proc.live.LinuxPtraceProc@665bad3e,pid=20304,state=running} in state "running" did not handle handleRemoval at frysk.proc.live.State.unhandled(State.java:67) at frysk.proc.live.LinuxPtraceProcState.handleRemoval(LinuxPtraceProcState.java:62) at frysk.proc.live.LinuxPtraceProc$1.execute(LinuxPtraceProc.java:332) at frysk.event.EventLoop.runEventLoop(EventLoop.java:365) at frysk.event.EventLoop.run(EventLoop.java:482) at frysk.gui.Gui$5.run(Gui.java:355) at java.lang.Thread.run(libgcj.so.8rh)