Public bug reported: Apologies, I don't know the exact text of the dialog box, so it's lightly paraphrased (I couldn't find the entire text in the locale files either).
SUMMARY I believe what is happening is when lubuntu-software-center runs in the background to check for updates, a failure to download indexes may cause this error, which pops up out of nowhere with no explanation. SETUP Do nothing, run lubuntu as normal. This may be triggered by a failure to download package indexes but I have not verified that. WHAT ACTUALLY HAPPENS Eventually, a "Software updater" dialog will appear, declaring something like "Downloading files failed. Please check your Internet connection." There is no other explanation and in my experience the dialog appears under other windows. WHAT I EXPECT TO HAPPEN A tasktray icon and/or notification would be best; failing that, some kind of dialog with more useful information. ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: lubuntu-software-center 0.0.10-0ubuntu2 ProcVersionSignature: Ubuntu 4.4.0-34.53-generic 4.4.15 Uname: Linux 4.4.0-34-generic x86_64 NonfreeKernelModules: wl ApportVersion: 2.20.1-0ubuntu2.1 Architecture: amd64 CurrentDesktop: LXDE Date: Thu Sep 8 14:58:11 2016 EcryptfsInUse: Yes PackageArchitecture: all SourcePackage: lubuntu-software-center UpgradeStatus: No upgrade log present (probably fresh install) ** Affects: lubuntu-software-center (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 apport-bug third-party-packages xenial -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1621649 Title: "Downloading files failed" dialog appears from nowhere To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lubuntu-software-center/+bug/1621649/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs