"Downloading files failed" dialog appears from nowhere

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)