When apt-cacher-ng is set as global apt proxy
> $ cat /etc/apt/apt.conf.d/apt-cacher
> Acquire::http { Proxy "http://localhost:3142"; };
the ubuntu-release-upgrader tool will use the proxy setting to access the release notes [1] on archive.ubuntu.com. These will be answered by apt-cacher-ng with 403 denied making the release notes unavailable for no apparent reason.
[1] http://archive.ubuntu.com/ubuntu/dists/vivid-updates/main/dist-upgrader-all/current/ReleaseAnnouncement.html
ProblemType: Bug
DistroRelease: Ubuntu 15.10
Package: apt-cacher-ng 0.8.5-1
ProcVersionSignature: Ubuntu 4.2.0-16.19-generic 4.2.3
Uname: Linux 4.2.0-16-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.19.1-0ubuntu3
Architecture: amd64
CurrentDesktop: KDE
Date: Tue Oct 20 11:19:31 2015
InstallationDate: Installed on 2013-10-29 (720 days ago)
InstallationMedia: Kubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
SourcePackage: apt-cacher-ng
UpgradeStatus: Upgraded to wily on 2015-10-19 (0 days ago)
modified.conffile..etc.apt.cacher.ng.security.conf: [inaccessible: [Errno 13] Permission denied: '/etc/apt-cacher-ng/security.conf']
echo VfilePatternEx:
And restart the service.
This is a stop-gap solution. Remove that conf file later when the pattern is added to the regular list.