There is a special kind of frustration reserved for the image that works. You open https://yoursite.com/og/launch.png in a tab, it loads instantly, it looks great. You paste the page into LinkedIn and get a headline, a domain, and no picture. Most write-ups about broken link previews stop at "make sure og:image is set". This post is about the next layer: the tag is set, the file exists, and the crawler still can't use it. Almost every case I've debugged comes down to one of six URL-level ...