I haven’t been using Safari much for a while, but after Sierra came out I started getting a lot of requests to update my TabLinks extension. I hadn’t planned to, but then looked into it and realized it was just a codesigning issue. But you know me, I had to update everything else, too.
This is a companion discussion topic for the original entry at https://brettterpstra.com/2016/10/31/tablinks-3-dot-0