I'm running apt-cacher ng on an Ubuntu Hardy server and try to upgrade the packages on a Natty client (which was initially a Maverick). I didn't do anything on the server. On the client I tried two setups. I configure APT to use a http-proxy. On the client I did a "apt-get update" which worked fine, but very slowly. In the acng-report.html I see an entry, which seems to be correct. After verifying Install these packages without verification [y/N]? y "apt-get upgrade" failes with the message: Err http://archive.ubuntu.com/ubuntu/ natty-updates/main libnux-0.9-common all 0.9.48-0ubuntu1.1 503 Name or service not known The GUI update manager fails as well with the message, that untrusted packages will be installed. I edit sources.list and add the server in the correct format to all sources. "apt-get update" is very slowly... and I get a lot of errors like this: W: Failed to fetch http://[::ffff:10.10.10.10]:3142/archive.ubuntu.com/ubuntu/dists/natty/main/binary-i386/Packages 403 Forbidden file type or location After that "apt-get upgrade" says: 0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded. What could be wrong? Is it possible to use apt-cacher ng on an older system for upgrading newer systems? Thank you in advance!