Failed to fetch error on apt-get update

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

Err:1 xenial InRelease Could not resolve host: deb.packager.io
Hit:2 xenial InRelease
Hit:3 xenial-updates InRelease
Hit:4 xenial-backports InRelease
Hit:5 xenial InRelease
Hit:6 xenial-security InRelease
Hit:7 xenial InRelease
Reading package lists... Done
W: Failed to fetch 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?

1 Answer

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.