Ubuntu 16.04 will not accept the plastic repos, it complains that:
W: https://www.plasticscm.com/plasticrepo/plasticscm-common/Ubuntu_14.04/./Release.gpg: Signature by key FC547B45E1BB2D5BA32CFB6A9A847BB1704CBB6B uses weak digest algorithm (SHA1) W: https://www.plasticscm.com/plasticrepo/plasticscm-latest/Ubuntu_14.04/./Release.gpg: Signature by key BEA0651E0EE3CBC4CF25092A3A8583CE515E508F uses weak digest algorithm (SHA1) E: Failed to fetch No Hash entry in Release file /var/lib/apt/lists/partial/www.plasticscm.com_plasticrepo_plasticscm-common_Ubuntu%5f14.04_._Release which is considered strong enough for security purposes E: Failed to fetch No Hash entry in Release file /var/lib/apt/lists/partial/www.plasticscm.com_plasticrepo_plasticscm-latest_Ubuntu%5f14.04_._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.
Update: I see now I already posted about this a while ago in installation and that I should just download the client zip file. I have done that and it works.
However, it would be much better if the ubuntu package could be updated to be signed with a valid key. Having an invalid installation package will most likely turn off most people evaluating plastic on linux and prevent them from considering it