Failed to fetch error on apt-get update

Question

I'm having an issue when running sudo apt-get update. I always get this error:

Err:1 https://deb.packager.io/gh/opf/openproject-ce xenial InRelease
  Could not resolve host: deb.packager.io
Hit:2 http://us.archive.ubuntu.com/ubuntu xenial InRelease
Hit:3 http://us.archive.ubuntu.com/ubuntu xenial-updates InRelease
Hit:4 http://us.archive.ubuntu.com/ubuntu xenial-backports InRelease
Hit:5 http://ppa.launchpad.net/certbot/certbot/ubuntu xenial InRelease
Hit:6 http://security.ubuntu.com/ubuntu xenial-security InRelease
Hit:7 https://download.docker.com/linux/ubuntu xenial InRelease
Reading package lists... Done
W: Failed to fetch https://deb.packager.io/gh/opf/openproject-ce/dists/xenial/InRelease  Could not resolve host: deb.packager.io
W: Some index files failed to download. They have been ignored, or old ones used instead.

I don't understand why apt is trying to fetch the package openproject on update. I removed the whole package and also ran sudo apt-get purge openproject but I still get the same error.

Any idea how to fix this?

Solution

Command apt-get update does not update the system, but merely the list of available packages. So it's not trying to fetch the package, but a list of packages from that URL. You need to check file /etc/apt/sources.list, as well as files from directory /etc/apt/sources.list.d/ for lines containing URL deb.packager.io and comment them out. More details in the documentation.

Once apt-get update updates the list of packages, you can upgrade the system with either apt-get upgrade or apt-get dist-upgrade. The difference is explained in an answer to this question on AskUbuntu.

Comments

[mrtnmgs]

Thanks! For some reason OpenProjects put a file under /etc/apt/sources.list.d/...

[Konrad Botor]

It's a common practice to ensure you get the newest version of the package from the developer's repository rather than the older one from main repository of your distribution or so you can get upgrades for given package at all when you install it directly from .deb file rather than repository.