There's reports of this in focal, too, now. See dupes of this ticket. It's still not clear how this comes about.
** Summary changed: - apt-cacher-ng can't be installed on xenial + wrong file permissions on /var/log/apt-cacher-ng abort package installation -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1512780 Title: wrong file permissions on /var/log/apt-cacher-ng abort package installation To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apt-cacher-ng/+bug/1512780/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs