And finally, by "bisection", I identified the package which was causing the warning: tortoisehg (or some of its dependencies).
I had installed this package with "sudo apt-get install tortoisehg". So now I ran "sudo apt-get install tortoisehg" from a command line and I got this prompt: WARNING: The following packages cannot be authenticated! tortoisehg mercurial mercurial-common Install these packages without verification? [y/N] Why on earth doesn't Update Manager just give the same prompt and the same Yes/No option? That's the issue. I'll change this to Verified because I think the source of the issue is pretty clear and it's nonsense to wait for some other random person to stumble into the problem, wnich is easily reproducible. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1371942 Title: "this requires installation of untrusted packages": incomplete warning, then "OK" button does nothing To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/update-manager/+bug/1371942/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
