When I add app into favorite list, icon is added. But when Plasma is quit and launch, app favorite list stay empty. Problem appear when you do a regular logout, kill plasmashell etc ...
So, I have more check Plasmashell output, and I have get a error in kactivies Database. KActivities: Database connection: "kactivities_db_resources_140054480578816_readonly" query_only: QVariant(qlonglong, 1) journal_mode: QVariant(QString, "wal") wal_autocheckpoint: QVariant(qlonglong, 100) synchronous: QVariant(qlonglong, 0) [Error at ResultSetPrivate::initQuery]: QSqlError("11", "Impossible de r�cup�rer la ligne", "database disk image is malformed") Closing SQL connection: "kactivities_db_resources_140054480578816_readonly" After search, I have renamed ~/.local/share/kactivitymanagerd/ to ~/.local/share/kactivitymanagerd.old/ and restart kactivitymanagerd and plasmashell. And actually favorites are OK. I close this bug :)