According to this: https://bugs.kde.org/show_bug.cgi?id=376347 QT 5.7 causes that bug. (kdialog crashes) AFAIK, in KDE Neon User Edition, Qt is provided by the package libqt5core5a/xenial,now 5.7.1+dfsg-3+16.04+build5 which is an Ubuntu package, not a neon one. So the question is: Is there anyway to upgrade Qt to 5.8 in KDE Neon User edition 5.9.1?
Why doesn't KDE neon maintain the package libqt5core5a? // Sorry I can't find any button to edit the above comment. Does it exist?
*** This bug has been marked as a duplicate of bug 376468 ***