I run multiple Ubuntu 20.04 servers on several Proxmox Hypervisors.
1 server has just encountered an issue with its apt updates but the other servers are all OK. Ubuntu server versions are all the same (20.04.2) and all are just running CLI.
All server /etc/apt/sources.list are identical The error I'm seeing on the 1 server is
Err:1 http://security.ubuntu.com/ubuntu focal-security InRelease
400 Bad Request [IP: 91.189.91.39 80]
Err:2 http://ubuntu.mirror.serversaustralia.com.au/ubuntu focal InRelease
400 Bad Request [IP: 27.50.85.5 80]
Reading package lists...
E: The repository 'http://security.ubuntu.com/ubuntu focal-security InRelease' is not signed.
E: Failed to fetch http://security.ubuntu.com/ubuntu/dists/focal-security/InRelease 400 Bad Request [IP: 91.189.91.39 80]
E: The repository 'http://ubuntu.mirror.serversaustralia.com.au/ubuntu focal InRelease' is not signed.
E: Failed to fetch http://ubuntu.mirror.serversaustralia.com.au/ubuntu/dists/focal/InRelease 400 Bad Request [IP: 27.50.85.5 80]
All other servers are updating fine, are all on the same subnet, same DNS, gateway etc. Below is the same "sudo apt update" command executed on one of the other servers
Hit:1 http://ubuntu.mirror.serversaustralia.com.au/ubuntu focal InRelease
Hit:2 http://security.ubuntu.com/ubuntu focal-security InRelease
Reading package lists...
Building dependency tree...
Reading state information...
All packages are up to date.
I attempted to install "inetutils-traceroute" but can't do that as the repos are broken. I can traceroute to security.ubuntu.com from any of the other servers no problems.
This is a production server and I could roll-back to a previous snapshot but confident the clever community out there can point me in the right direction. As this is a production server, I don't 'play' with its settings.