Typically, web-browsers such as Firefox have their own proxy settings. The global network proxy setting in Gnome may not be transferring over to KDE due to an oddity in knetworkmanager.
Try setting up your proxy in KDE using knetworkmanager (should show up in the system tray automatically at boot), and trying the update again. Thank you for your patience with this issue, I wish I had a more definitive solution for you. -- Getting Upgrade prerequisites failed https://bugs.launchpad.net/bugs/155922 You received this bug notification because you are a member of Ubuntu Bugs, which is the bug contact for Ubuntu. -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs