What we see from your debug output is that gpgv is not returning any sensible information:
Summary: Good: Bad: Worthless: SoonWorthless: NoPubKey: You could try running apt-key verify manually on a few InRelease files (like apt-key verify /var/lib/apt/lists/archive.ubuntu.com_ubuntu_dists_xenial_InRelease) and see if that gives us any clue - or at least look at the files (especially in partial/), maybe they are garbage. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1642386 Title: At least one invalid signature was encountered. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apt/+bug/1642386/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
