Comment 2 for bug 1995896

Hi Lars,

This is due to your use of mirror://mirrors.ubuntu.com/mirrors.txt in your /etc/apt/sources.list. When ubuntu-release-upgrader checks if your current mirror is reachable, it does not know how to check mirror:// URIs.

As a workaround, please use a single mirror (e.g. http://no.archive.ubuntu.com/ubuntu) in your /etc/apt/sources.list, and then do the upgrade. You should be able to switch back to mirrors://mirrors.ubuntu.com/mirrors.txt after the upgrade.