All PPAs I have, on the site launchpad says are compatible with Ubuntu 16.04
W: gpgv:/var/lib/apt/lists/dl.google.com_linux_chrome_deb_dists_stable_Release.gpg: The repository is insufficiently signed by key 4CCA1EAF950CEE4AB83976DCA040830F7FAC5991 (weak digest)
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_libreoffice_libreoffice-5-1_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key 36E81C9267FD1383FCC4490983FBA1751378B444 (weak digest)
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_maarten-baert_simplescreenrecorder_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key 4DEDB3E05F043CA185176AC0409C8B51283EC8CD (weak digest)
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_otto-kesselgulasch_gimp_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key FB97E9C3A97F85C095AEA7903BDAAC08614C4B38 (weak digest)
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_sunab_kdenlive-release_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key 6976C1CEB06586061C2C0472B5115B98AA836CA8 (weak digest)
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_webupd8team_atom_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key 7B2C3B0889BF5709A105D03AC2518248EEA14886 (weak digest)
W: gpgv:/var/lib/apt/lists/ppa.launchpad.net_webupd8team_java_ubuntu_dists_xenial_InRelease: The repository is insufficiently signed by key 7B2C3B0889BF5709A105D03AC2518248EEA14886 (weak digest)
Only Megasync I downloaded the deb
W: gpgv:/var/lib/apt/lists/mega.nz_linux_MEGAsync_xUbuntu%5f15.04_._Release.gpg: The repository is insufficiently signed by key BF8B66E01192CBA2E72201294B4E7A9523ACD201 (weak digest)
All PPAs I have, on the site launchpad says are compatible with Ubuntu 16.04
W: gpgv:/var/ lib/apt/ lists/dl. google. com_linux_ chrome_ deb_dists_ stable_ Release. gpg: The repository is insufficiently signed by key 4CCA1EAF950CEE4 AB83976DCA04083 0F7FAC5991 (weak digest)
W: gpgv:/var/ lib/apt/ lists/ppa. launchpad. net_libreoffice _libreoffice- 5-1_ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key 36E81C9267FD138 3FCC4490983FBA1 751378B444 (weak digest)
W: gpgv:/var/ lib/apt/ lists/ppa. launchpad. net_maarten- baert_simplescr eenrecorder_ ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key 4DEDB3E05F043CA 185176AC0409C8B 51283EC8CD (weak digest)
W: gpgv:/var/ lib/apt/ lists/ppa. launchpad. net_otto- kesselgulasch_ gimp_ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key FB97E9C3A97F85C 095AEA7903BDAAC 08614C4B38 (weak digest)
W: gpgv:/var/ lib/apt/ lists/ppa. launchpad. net_sunab_ kdenlive- release_ ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key 6976C1CEB065860 61C2C0472B5115B 98AA836CA8 (weak digest)
W: gpgv:/var/ lib/apt/ lists/ppa. launchpad. net_webupd8team _atom_ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key 7B2C3B0889BF570 9A105D03AC25182 48EEA14886 (weak digest)
W: gpgv:/var/ lib/apt/ lists/ppa. launchpad. net_webupd8team _java_ubuntu_ dists_xenial_ InRelease: The repository is insufficiently signed by key 7B2C3B0889BF570 9A105D03AC25182 48EEA14886 (weak digest)
Only Megasync I downloaded the deb
W: gpgv:/var/ lib/apt/ lists/mega. nz_linux_ MEGAsync_ xUbuntu% 5f15.04_ ._Release. gpg: The repository is insufficiently signed by key BF8B66E01192CBA 2E72201294B4E7A 9523ACD201 (weak digest)