OwnCloud 10.0.9 Mac OS X 10.13.6 (High Sierra), Problem sync Contacts (CardDav)v

Hey,

maybe existing posts like this are helping you on how to configure your client:

I also did a short search like https://github.com/owncloud/core/search?q=“Invalid+or+unknown+sync+token”&type=Issues and found some other posts about the log entries you’re getting: