Rated 4 out of 5 stars
Why this extension is not working on this latest version of thunderbird?This review is for a previous version of the add-on (3.0.0).
It wasn't working because it is difficult to keep up with the rate of change in Thunderbird. They keep removing features that gContactSync uses, and don't have updated documentation to help add-on developers migrate to newer versions. Version 3.1.4 should work better, but requires TB 65 or later, which is still in beta.