Comment 6 for bug 1587204

I am also getting this with 18.04.5 LTS. In /etc/apt/apt.conf.d/99proxy I have:

Acquire::http::Proxy "http://127.0.0.1:3142/";
Acquire::https::Proxy "DIRECT";

and sometimes the the motd displays

proxy 'DIRECT' looks invalid

I have discovered why it's intermittent: that text is the *stderr* output from /usr/lib/ubuntu-release-upgrader/check-new-release -q

This means it doesn't get stored in /var/lib/ubuntu-release-upgrader/release-upgrade-available, because only the *stdout* is redirected there.

Therefore, it only gets displayed at login time when /usr/lib/ubuntu-release-upgrader/release-upgrade-motd is run, and this only performs the check if its previous output is more than 1 day old.

I also note that the script runs "check-new-release -q" in the background (with &), which means that its stderr output could in principle appear later on and be mixed up with other output. Perhaps this is intentional, so that messages like "Failed to connect to https://changelogs.ubuntu.com/meta-release-lts. Check your Internet connection or proxy settings" don't persist in the motd.

But in any case, "DIRECT" is a documented and valid form for proxy, so it should not generate any warning.