I just ran sudo apt update, as the first step in upgrading from 20.04 to 22.04. This was part of the response:
Get:17 http://gb.archive.ubuntu.com/ubuntu focal-updates/main amd64 DEP-11 Metadata [275 kB]
Err:11 https://www.getdeb.net/ubuntu focal-getdeb Release 404 Not Found [IP: 206.189.192.106 443]
Get:18 http://gb.archive.ubuntu.com/ubuntu focal-updates/universe amd64 Packages [1,046 kB]
... I've skipped a few lines here...
Get:33 http//gb.archive.ubuntu.com/ubuntu focal-backports/universe amd64 c-n-f Metadata [880 B]
Reading package lists... Done
E: The repository 'http://archive.getdeb.net/ubuntu focal-getdeb Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
OK. So why is the update trying to use https when the path in my Software & Update settings is http://archive.getdeb.net...?
Cheers
JM