You can update your system with unsupported packages from this untrusted PPA by adding ppa:qbittorrent-team/qbittorrent-stable to your system's Software Sources. ( Read about installing ) sudo add-apt-repository ppa:qbittorrent-team/qbittorrent-stable sudo apt update Technical details about this PPA

This PPA can be added to your system manually by copying the lines below and adding them to your system's software sources.