To force a full refresh of the package database and update all packages on the system. It may necessary when [[Special:MyLanguage/Switching_Branches|switching branches]] or [[Special:MyLanguage/Pacman-mirrors|switching mirrors]] to avoid inconsistent metadata. Inconsistent metadata will be obvious if you get '''404 Not Found''' for certain packages.
To force a full refresh of the package database and update all packages on the system. You must do this when switching branches or switching mirrors.