I'm having the same issue with the google talk plugin, remmina, shutter, and variety:
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_peterlevi_ppa_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key 876E675CB1AABA3494F27BA6C45A53C1A546BE4F (weak digest)
W: gpgv:/var/lib/apt/lists/partial/dl.google.com_linux_talkplugin_deb_dists_stable_Release.gpg: The repository is insufficiently signed by key 4CCA1EAF950CEE4AB82976DCA040830F7FAC5991 (weak digest)
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_remmina-ppa-team_remmina-next_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key 04E38CE134B269B9F38F82EE8A993C2521C5F0BA (weak digest)
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_shutter_ppa_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key 5017D4931D0ACADE295B68ADFC6D8D9D009ED615 (weak digest)
W: Failed to fetch http://dl.google.com/linux/talkplugin/deb/dists/stable/Release No Hash entry in Release file /var/lib/apt/lists/partial/dl.google.com_linux_talkplugin_deb_dists_stable_Release, which is considered strong enough for security purposes
E: Some index files failed to download. They have been ignored, or old ones used instead.
I'm having the same issue with the google talk plugin, remmina, shutter, and variety:
W: gpgv:/var/ lib/apt/ lists/ppa. launchpad. net_peterlevi_ ppa_ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key 876E675CB1AABA3 494F27BA6C45A53 C1A546BE4F (weak digest) lib/apt/ lists/partial/ dl.google. com_linux_ talkplugin_ deb_dists_ stable_ Release. gpg: The repository is insufficiently signed by key 4CCA1EAF950CEE4 AB82976DCA04083 0F7FAC5991 (weak digest) lib/apt/ lists/ppa. launchpad. net_remmina- ppa-team_ remmina- next_ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key 04E38CE134B269B 9F38F82EE8A993C 2521C5F0BA (weak digest) lib/apt/ lists/ppa. launchpad. net_shutter_ ppa_ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key 5017D4931D0ACAD E295B68ADFC6D8D 9D009ED615 (weak digest) dl.google. com/linux/ talkplugin/ deb/dists/ stable/ Release No Hash entry in Release file /var/lib/ apt/lists/ partial/ dl.google. com_linux_ talkplugin_ deb_dists_ stable_ Release, which is considered strong enough for security purposes
W: gpgv:/var/
W: gpgv:/var/
W: gpgv:/var/
W: Failed to fetch http://
E: Some index files failed to download. They have been ignored, or old ones used instead.