We made things work better for unreadable files, so I think that's fixed in cosmic and probably bionic.
** Changed in: apt (Ubuntu) Status: In Progress => Fix Released -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to apt in Ubuntu. https://bugs.launchpad.net/bugs/849736 Title: apt-cache policy silently shows inaccurate information when any file in /etc/apt/sources.list.d is unreadable Status in apt package in Ubuntu: Fix Released Bug description: Version: 0.8.16~exp5ubuntu8 Release: 11.10 I've noticed some odd behaviour from apt-cache policy where it pretends, without protest, that package versions in PPAs don't exist. The trigger seems to be a newly-added source whose .list file I set up to be only readable by root (it contains authentication information). When any file in /etc/apt/sources.list.d is unreadable, apt-cache won't try to read further files, and it also apparently discards information from any of the files it did manage to read. (Assuming it reads them as it goes — I was only tracing calls to open(2).) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apt/+bug/849736/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp