Aha! I think it is that for some weird reason, a SHA-384 certificate may be the cause of this problem. I changed my server certificate to SHA-1 and TLS 1.2 works again. (and CUPS uses GnuTLS, so my OpenSSL cannot be the problem)
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1526999 Title: cups is intolerant to TLS 1.2 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/cups/+bug/1526999/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs