In my Slackware (current) running KDE Plasma 5.16.5 have the similar error.

Code: Select all

kf5.kio.core: couldn't create slave: "klauncher said: Error loading '/usr/lib64/qt5/plugins/kf5/kio/tags.so'."
kf5.kio.core: "Unable to create io-slave. klauncher said: Error loading '/usr/lib64/qt5/plugins/kf5/kio/tags.so'."

This error occurs starting much programs like gwenview, dolphin, ...

After upgrade QT to 5.

The error was solved upgrading this packages:

glib2
glibmm
taglib
taglib-extras
qt-gstreamer
qtscriptgenarator
polkit-qt
kqtquickcarts

All these packages are not necessary, but I did it. SOLVED TO ME.