Journactl shows:

Jan 29 14:33:30 localhost.localdomain kwin_x11[1311]: qt.qpa.xcb: QXcbConnection: XCB error: 3 (BadWindow), sequence: 5976, resource id: 44041915, major code: 18 (ChangeProperty), minor code: 0
Jan 29 14:33:30 localhost.localdomain kwin_x11[1311]: qt.qpa.xcb: QXcbConnection: XCB error: 3 (BadWindow), sequence: 5981, resource id: 44041916, major code: 18 (ChangeProperty), minor code: 0
Jan 29 14:33:32 localhost.localdomain drkonqi[3016]: org.kde.drkonqi: Unable to find an internal debugger that can work with the KCrash backend
Jan 29 14:33:32 localhost.localdomain plasmashell[1317]: QQuickItem::stackAfter: Cannot stack StatusNotifierItem_QMLTYPE_269(0x55e8c5a79ba0, parent=0x55e8c3ab9790, geometry=0,0 0x0) after StatusNotifierItem_QMLTYPE_269(0x55e8c66a6630), which must be a sibling
Jan 29 14:33:32 localhost.localdomain plasmashell[1317]: file:///usr/share/plasma/plasmoids/org.kde.plasma.notifications/contents/ui/NotificationDelegate.qml:113: ReferenceError: appIcon is not defined

If you can install gdb, so drkonqi can provide a backtrace, that would help debugging.

Here is the backtrace :)


Application: KSieve Editor (sieveeditor), signal: Segmentation fault
Using host libthread_db library "/lib64/libthread_db.so.1".
[Current thread is 1 (Thread 0x7fb345378980 (LWP 2258))]

Thread 4 (Thread 0x7fb334c1e700 (LWP 2262)):
#0  0x00007fb3519a8284 in read () from /lib64/libc.so.6
#1  0x00007fb350428870 in ?? () from /lib64/libglib-2.0.so.0
#2  0x00007fb3503e0bab in g_main_context_check () from /lib64/libglib-2.0.so.0
#3  0x00007fb3503e1060 in ?? () from /lib64/libglib-2.0.so.0
#4  0x00007fb3503e11e0 in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#5  0x00007fb351f1b5ab in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Core.so.5
#6  0x00007fb351ec9e0b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Core.so.5
#7  0x00007fb351d31e86 in QThread::exec() () from /lib64/libQt5Core.so.5
#8  0x00007fb351d3b2fb in ?? () from /lib64/libQt5Core.so.5
#9  0x00007fb350dc85a3 in start_thread () from /lib64/libpthread.so.0
#10 0x00007fb3519b7633 in clone () from /lib64/libc.so.6

Thread 3 (Thread 0x7fb335f6a700 (LWP 2261)):
#0  0x00007fb3519ac721 in poll () from /lib64/libc.so.6
#1  0x00007fb3503e10b6 in ?? () from /lib64/libglib-2.0.so.0
#2  0x00007fb3503e11e0 in g_main_context_iteration () from /lib64/libglib-2.0.so.0
#3  0x00007fb351f1b5ab in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Core.so.5
#4  0x00007fb351ec9e0b in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /lib64/libQt5Core.so.5
#5  0x00007fb351d31e86 in QThread::exec() () from /lib64/libQt5Core.so.5
#6  0x00007fb350df9f89 in ?? () from /lib64/libQt5DBus.so.5
#7  0x00007fb351d3b2fb in ?? () from /lib64/libQt5Core.so.5
#8  0x00007fb350dc85a3 in start_thread () from /lib64/libpthread.so.0
#9  0x00007fb3519b7633 in clone () from /lib64/libc.so.6

Thread 2 (Thread 0x7fb338150700 (LWP 2260)):
#0  0x00007fb3519ac721 in poll () from /lib64/libc.so.6
#1  0x00007fb35037339f in ?? () from /lib64/libxcb.so.1
#2  0x00007fb35037501a in xcb_wait_for_event () from /lib64/libxcb.so.1
#3  0x00007fb338282bf9 in ?? () from /lib64/libQt5XcbQpa.so.5
#4  0x00007fb351d3b2fb in ?? () from /lib64/libQt5Core.so.5
#5  0x00007fb350dc85a3 in start_thread () from /lib64/libpthread.so.0
#6  0x00007fb3519b7633 in clone () from /lib64/libc.so.6

Thread 1 (Thread 0x7fb345378980 (LWP 2258)):
[KCrash Handler]
#6  0x00007fb3527b8139 in QAction::setEnabled(bool) () from /lib64/libQt5Widgets.so.5
#7  0x00007fb352df2267 in SieveEditorMainWindow::slotUpdateActions() () from /lib64/libsieveeditor.so.5
#8  0x00007fb352df2913 in SieveEditorMainWindow::slotSystemNetworkOnlineStateChanged(bool) () from /lib64/libsieveeditor.so.5
#9  0x00007fb352df6e45 in SieveEditorMainWindow::SieveEditorMainWindow(QWidget*) () from /lib64/libsieveeditor.so.5
#10 0x000055a8caf36879 in ?? ()
#11 0x00007fb3518deee3 in __libc_start_main () from /lib64/libc.so.6
#12 0x000055a8caf3690e in _start ()
[Inferior 1 (process 2258) detached]

Tested with F30 Beta Fedora-KDE-Live-x86_64-30-1.1 and am still seeing this bug.

Proposed as a Blocker for 30-final by Fedora user coremodule using the blocker tracking app because:

 Proposing as a blocker as it seems to violate the following Final critieria:

"All applications that can be launched using the standard graphical mechanism of a release-blocking desktop after a default installation of that desktop must start successfully and withstand a basic functionality test."

I'm giving myself an hour or two to see if I can fix this crash before we try and take the app out.

Discussed in the Fedora 30 Go/No-Go meeting blocker review:
https://meetbot.fedoraproject.org/fedora-meeting-1/2019-04-25/f30-final-go_no_go-meeting.2019-04-25-17.01.log.html#l-582

Accepted as a blocker because it violates the following Final criteria:
"All applications that can be launched using the standard graphical mechanism of a release-blocking desktop after a default installation of that desktop must start successfully and withstand a basic functionality test."

pim-sieve-editor-18.12.2-2.fc30 has been submitted as an update to Fedora 30. https://bodhi.fedoraproject.org/updates/FEDORA-2019-e5343ff7b6

Reported upstream,
https://bugs.kde.org/show_bug.cgi?id=406902

It works on rc2 live

I can confirm, that it works on RC2 Live. I will also try Netinst.

I am sorry, but when the KDE spin is installed from Netinst, the KSieve editor still does not start. I do not consider the problem to be fixed and thus the blocker stays.

Now, I see that repositories still have the old version, because mine is still 18.12.2-1. So the problem might be fixed then. I will try to upgrade later and see.

pim-sieve-editor-18.12.2-2.fc30 fixes the issue.

Tested pim-sieve-editor-18.12.2-2.fc30 with Fedora-KDE-Live-x86_64-30-1.2. Works as it should, no trouble found.

pim-sieve-editor-18.12.2-2.fc30 has been pushed to the Fedora 30 stable repository. If problems still persist, please make note of it in this bug report.