hi,
after Tumbleweed update, openSUSE-release-20150909-1.2.x86_64, all entries in the
-Application Launcher --Applications menu were lost,
the only way found to re-active them was a forced re-install of :-
<> kdelibs4-4.14.10-1.1.x86_64
<> kservice-5.13.0-1.1.x86_64
<> plasma5-pa-5.4.0-1.1.x86_64
hths
Maybe your system was not fully updated for some reason?
Patches have been added to kconfig and kservice to read translated Applications menu (and others like systemsettings5) entries from the package “desktop-translations” (like it was done in KDE3 and KDE4) to make them translated again.
If you updated only one of the two packages, this would definitely break reading the entries completely…
I have seen no problem on a fresh installation of 20150909 at least.
Btw, kdelibs4 and plasma5-pa are completely unrelated to Plasma5’s application launcher/menu, but any re-installation of a package that contains a .desktop file will force KF5 to re-create the whole cache.
the choice of forced packages to be re-installed was to make sure both kde4 and plasma5 were correctly initialized.
info was taken from the package file lists.
as it worked first time no further analysis was done.
thx for the feedback
Ok, but kdelibs4 is only used by KDE4 applications (and not the Plasma5 application menu) which should not have been affected anyway, and plasma5-pa is a volume control applet definitely unrelated to this problem… 
What I imagine that could have happened is that kded5 recognized during the update that the files in /usr/share/applications/ (i.e. the menu entries) have been modified and decided to rebuild the menu entry cache (while the upgrade was not finished yet). At that moment the system was in an inconsistent state, so the cache got “broken”.
Such things can happen if you upgrade your system while inside KDE. To play safe you should do the upgrades in text mode. Not that I would recommend it, it was just an unfortunate situation which normally shouldn’t happen, and recently there have been changes upstream regarding this that should make it more safe (the cache is only checked/rebuild when applications actually try to access it, kded5 doesn’t monitor the files for changes any more)
But reinstalling those 3 packages probably triggered kded5 to rebuild the cache again as mentioned, which worked this time because both kservice and kconfig were updated already.
Running “kbuildsycoca5 --noincremental” (as user) to rebuild the cache probably would have fixed it too.
this worked on earlier updates
“kbuildsycoca5 --noincremental” had been tried prior to the --force re-installed with no effect on the lack of Application Launcher entries.
after running “kbuildsycoca5 --noincremental”, both from the cmd line and a terminal within kde a boot to the gui was only possible via the safey mode, otherwise a black screen.
after going through the safety mode to boot the following boots/re-boots were successful. others have already mentioned this happening-
thx again for the feedback
Well, I can only guess what happened on your system, I cannot know.
If the installed kservice and kconfig were incompatible at the time you ran kbuildsycoca5, the problem would persist.
after running “kbuildsycoca5 --noincremental”, both from the cmd line and a terminal within kde a boot to the gui was only possible via the safey mode, otherwise a black screen.
kbuildsycoca5 cannot really cause this. And if it did, booting to recovery mode (I suppose you mean that with “safey mode”) wouldn’t have worked either.
after going through the safety mode to boot the following boots/re-boots were successful. others have already mentioned this happening-
Have they?
I am only aware of some people reporting they had to delete the plasma config. And I see no relation to kbuildsycoca5 or the application launcher entries missing (and nobody mentioned having run kbuildsycoca5).