Comment 13 for bug 33861

I fixed it (at least for me). I started the notifier under the console and got this message:

adept_notifier: checking cache for upgradable packages...
adept_notifier: error checking cache for upgradable packages...
adept_notifier: what: ERROR: The list of sources could not be read.

I went digging, and found that all my *.list files in /etc/apt/sources.list.d were owned root.root and had 600 permissions. I'm not sure *why* they were that way, but somehow they had been created that way. I chmod'ed them 604 and started notifier: nice green circle.

So, it would appear adept_notifier wants to be able to read *all* the source lists, which only makes sense.