Update yesterday broke my task manager and main panel was just an icon of two little windows, clicking on it gives me the pop-up of:
Error loading QML file: file:///usr/share/plasma/plasmoids/org.kde.plasma.taskmanager/contents/ui/main.qml:26:1: plugin cannot be loaded for module "org.kde.taskmanager": Cannot load library /usr/lib/qt/qml/org/kde/taskmanager/libtaskmanagerplugin.so: (libprocesscore.so.7: cannot open shared object file: No such file or directory)
possible solution that worked for me to fix fix libksysguard
sudo rm /var/lib/pacman/local/libksysguard-5.14.3-1/ -rf sudo pacman -S libksysguard --force
I took this from solution from: https://www.reddit.com/r/kde/comments/9uu1zx/iconsonly_task_manager_and_regular_task_manager/
posting in case others have problems.