The share image's format isn't supported everywhere

Why it matters

Link-preview scrapers are years behind browsers on image formats. JPEG, PNG and GIF are the safe choice: LinkedIn lists exactly those three, and Facebook's page on share images names no format at all. X also documented WebP; nobody documents AVIF, and X said outright that SVG is not supported. An unsupported format doesn't produce an error anywhere: the preview just has no picture, on some networks, for some people.

Sources: LinkedIn: make your website shareable; Facebook: images in link shares. X's list is from its Cards documentation, since withdrawn.

How to fix it

Keep modern formats for the page itself and export the share image as PNG (flat graphics) or JPEG (photographs):

<meta property="og:image" content="https://www.example.com/share.png" />
<meta property="og:image:type" content="image/png" />

If an image CDN converts formats automatically, exclude this one file: scrapers don't send the Accept header it relies on, and some CDNs answer with WebP anyway.

Examples

These are the rule's own test pages, and what it says about each. They are run on every change to the rule book.

They differ only in what the server answered:

200 OK · image/svg+xml · 9 KB · 1200×630

WarningThe share image is image/svg+xml, which link previews don't support: most networks will show no picture.

fail-svg

200 OK · image/webp · 90 KB · 1200×630

NoticeThe share image is a WebP. X accepts it, but LinkedIn and Facebook only document JPEG, PNG and GIF, so some previews may have no picture.

fail-webp

200 OK · image/jpeg; charset=binary · 120 KB · 1200×630

PassedThe share image is a JPEG, which every network accepts.

pass-jpeg