Bug#711500: gnome-settings-daemon: "Could not get updates. Failed to process request. Operation was cancelled"

[Matthias Klumpp]

Hi!
Depending on your version of Aptd, this might very well be the case
that Aptd is blocking something. Newer versions of APtd will AFAIK
jump out of the way as soon as PackageKit is used.
Synaptic and unattended-upgrades shouldn't have any effect on
PackageKit, as long as they don't run permanently (and even if they
did, PK would simply wait until the database lock is released).
software-properties-gtk depending on Aptd is ugly, if the maintainers
allow it, I will commit a patch to remove that dependency, because it
isn't required for anything critical anyway.
The GSD patch mentioned above should fix the issue - can you maybe try
if removing Aptd would fix it too? Because something is apparently
cancelling PK transactions, and Synaptic etc. is unlikely, so my guess
would be Aptd (although even that would be weird).
Are you maybe performing actions on the Apt database or on PK
manually, while GSD checks for updates? (This is a bug in GSD anyway,
since it shouldn't nag users about cancelled background transactions,
but it should not happen often too)
Cheers,
    Matthias