Unfortunately, the backtrace isn't very helpful because you don't have any debugging information. Can you please try to obtain a backtrace with debugging information?
https://wiki.kubuntu.org/DebuggingKDE#Packages%20with%20Debugging%20Symbols

I've installed -dbg packages. And I did upgrade of all packages (last upgrade was 3 days ago) and bug seems to go away. ;o) Thank you for your time.

I'm so sorry but I have to tell you issue is here again:

Aplikace: Krusader (krusader), signál SIGABRT
[Thread debugging using libthread_db enabled]
[New Thread 0xb5c0f6c0 (LWP 13959)]
[KCrash handler]
#6  0xb7f49430 in __kernel_vsyscall ()
#7  0xb6408880 in raise () from /lib/tls/i686/cmov/libc.so.6
#8  0xb640a248 in abort () from /lib/tls/i686/cmov/libc.so.6
#9  0xb7178795 in qt_message_output () from /usr/lib/libQtCore.so.4
#10 0xb7178872 in qFatal () from /usr/lib/libQtCore.so.4
#11 0xb7178915 in qt_assert () from /usr/lib/libQtCore.so.4
#12 0xb741f950 in ?? () from /usr/lib/libkio.so.5
#13 0xb741faf0 in KIO::ListJob::qt_metacall () from /usr/lib/libkio.so.5
#14 0xb7285a60 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#15 0xb72867e2 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#16 0xb74e0733 in KIO::SlaveInterface::listEntries ()
   from /usr/lib/libkio.so.5
#17 0xb74e4399 in KIO::SlaveInterface::dispatch () from /usr/lib/libkio.so.5
#18 0xb74e0f67 in KIO::SlaveInterface::dispatch () from /usr/lib/libkio.so.5
#19 0xb74d0f8d in KIO::Slave::gotInput () from /usr/lib/libkio.so.5
#20 0xb74d39d3 in KIO::Slave::qt_metacall () from /usr/lib/libkio.so.5
#21 0xb7285a60 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#22 0xb72867e2 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#23 0xb73e1747 in KIO::Connection::readyRead () from /usr/lib/libkio.so.5
#24 0xb73e3819 in ?? () from /usr/lib/libkio.so.5
#25 0xb73e39a6 in KIO::Connection::qt_metacall () from /usr/lib/libkio.so.5
#26 0xb727ebfb in QMetaCallEvent::placeMetaCall ()
   from /usr/lib/libQtCore.so.4
#27 0xb7280771 in QObject::event () from /usr/lib/libQtCore.so.4
#28 0xb68f28ec in QApplicationPrivate::notify_helper ()
   from /usr/lib/libQtGui.so.4
#29 0xb68fa76e in QApplication::notify () from /usr/lib/libQtGui.so.4
#30 0xb7b1e72d in KApplication::notify () from /usr/lib/libkdeui.so.5
#31 0xb7270e61 in QCoreApplication::notifyInternal ()
   from /usr/lib/libQtCore.so.4
#32 0xb7271ae5 in QCoreApplicationPrivate::sendPostedEvents ()
   from /usr/lib/libQtCore.so.4
#33 0xb7271cdd in QCoreApplication::sendPostedEvents ()
   from /usr/lib/libQtCore.so.4
#34 0xb729b82f in ?? () from /usr/lib/libQtCore.so.4
#35 0xb5f976f8 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#36 0xb5f9ada3 in ?? () from /usr/lib/libglib-2.0.so.0
#37 0xb5f9af61 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#38 0xb729b478 in QEventDispatcherGlib::processEvents ()
   from /usr/lib/libQtCore.so.4
#39 0xb698cee5 in ?? () from /usr/lib/libQtGui.so.4
#40 0xb7271f36 in QCoreApplication::processEvents ()
   from /usr/lib/libQtCore.so.4
#41 0x0820b46e in vfs::vfs_processEvents (this=0x8a9f1e8)
    at /build/buildd/krusader-2.0~svn6078/krusader/VFS/vfs.cpp:251
#42 0x0822b818 in ftp_vfs::populateVfsList (this=0x8a9f1e8, 
    origin=@0xbfe4a368, showHidden=<value optimized out>)
    at /build/buildd/krusader-2.0~svn6078/krusader/VFS/ftp_vfs.cpp:196
#43 0x0820d72b in vfs::vfs_refresh (this=0x8a9f1e8, origin=@0xbfe4a368)
    at /build/buildd/krusader-2.0~svn6078/krusader/VFS/vfs.cpp:213
#44 0x080b8868 in ListPanelFunc::immediateOpenUrl (this=0x880bc20, 
    urlIn=@0x880bc50)
    at /build/buildd/krusader-2.0~svn6078/krusader/Panel/panelfunc.cpp:171
#45 0x080b98b8 in ListPanelFunc::doOpenUrl (this=0x880bc20)
    at /build/buildd/krusader-2.0~svn6078/krusader/Panel/panelfunc.cpp:259
#46 0x080bd703 in ListPanelFunc::qt_metacall (this=0x880bc20, 
    _c=QMetaObject::InvokeMetaMethod, _id=9, _a=0xbfe4a4a8)
    at /build/buildd/krusader-2.0~svn6078/obj-i486-linux-gnu/krusader/Panel/panelfunc.moc:94
#47 0xb7285a60 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#48 0xb72867e2 in QMetaObject::activate () from /usr/lib/libQtCore.so.4
#49 0xb72c07a7 in QTimer::timeout () from /usr/lib/libQtCore.so.4
#50 0xb728c40e in QTimer::timerEvent () from /usr/lib/libQtCore.so.4
#51 0xb728053f in QObject::event () from /usr/lib/libQtCore.so.4
#52 0xb68f28ec in QApplicationPrivate::notify_helper ()
   from /usr/lib/libQtGui.so.4
#53 0xb68fa76e in QApplication::notify () from /usr/lib/libQtGui.so.4
#54 0xb7b1e72d in KApplication::notify () from /usr/lib/libkdeui.so.5
#55 0xb7270e61 in QCoreApplication::notifyInternal ()
   from /usr/lib/libQtCore.so.4
#56 0xb729ed81 in ?? () from /usr/lib/libQtCore.so.4
#57 0xb729b520 in ?? () from /usr/lib/libQtCore.so.4
#58 0xb5f976f8 in g_main_context_dispatch () from /usr/lib/libglib-2.0.so.0
#59 0xb5f9ada3 in ?? () from /usr/lib/libglib-2.0.so.0
#60 0xb5f9af61 in g_main_context_iteration () from /usr/lib/libglib-2.0.so.0
#61 0xb729b478 in QEventDispatcherGlib::processEvents ()
   from /usr/lib/libQtCore.so.4
#62 0xb698cee5 in ?? () from /usr/lib/libQtGui.so.4
#63 0xb726f52a in QEventLoop::processEvents () from /usr/lib/libQtCore.so.4
#64 0xb726f6ea in QEventLoop::exec () from /usr/lib/libQtCore.so.4
#65 0xb7271da5 in QCoreApplication::exec () from /usr/lib/libQtCore.so.4
#66 0xb68f2767 in QApplication::exec () from /usr/lib/libQtGui.so.4
#67 0x08090c92 in main (argc=3, argv=0xbfe4abf0)
    at /build/buildd/krusader-2.0~svn6078/krusader/main.cpp:264
#0  0xb7f49430 in __kernel_vsyscall ()

It happens after try to run any .deb package. Always the same bug.

I think this is a KIO bug, reassigning. Please bounce back if you think otherwise.

Is this still valid on a current KDE version ? If you can still reproduce, can you install the "kdelibs5-dbg" package to get a more complete backtrace?
Thanks!

It's OK. Thank you.