This question already has an answer here:
My update manager shows updates available. When I click on install updates it shows the following and does not update.
The action would require the installation of packages from not authenticated sources.
accountsservice cups cups-bsd cups-client cups-common cups-ppdc empathy empathy-common libaccountsservice0 libcups2 libcupscgi1 libcupsdriver1 libcupsimage2 libcupsmime1 libcupsppdc1 nautilus-sendto-empathy scribus-trunk
How to get updates ?