Cannot upload new contact from Thunderbird to MacOS Cardbook for Thunderbird › Forums › Main Forum › Cannot upload new contact from Thunderbird to MacOS This topic contains 1 reply, has 1 voice, and was last updated by TomMach 1 week, 6 days ago. Author Posts 7th September 2019 at 23:50 #2684 TomMachParticipant Hello, i have thunderbird version 68.0 and CardBook 41.6 CardDav server is MacOS HighSierra. iPhone sync is fine. From CardBook I cannot upload new contact with error code 412 Precondition Failed. Please can you help me. Best Tomas. 8th September 2019 at 00:13 #2685 TomMachParticipant My function iPhone use port 8843 SSL on Contacts CardBook use port 443 SSL On Mac Server is self signed certificate – in Thunderbird certificate allow exception this certificate. Thank Tomas Author Posts You must be logged in to reply to this topic.